Name: experimental procedure for laboratory studies of in situ burning : flammability and burning efficiency of crude oil
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<p class="jove_content">The authors would like to thank the Danish Council for Independent research for funding the project (Grant DDF - 1335-00282). COWIfonden funded the construction of the Crude Oil Flammability Apparatus and the gas analyzer, including the duct insert. Maersk Oil and Statoil provided the crude oils that were used for the representative results. None of the sponsors have been involved in the protocol or the results of this paper. The authors would also like to thank Ulises Rojas Alva for assistance with constructing the modified cone sample holder.</p>

<ol>
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<p class="jove_content">The authors have nothing to disclose.</p>

<p class="jove_content">The two weathering methods discussed in this paper are a relatively simple approximation of the weathering processes that a spilled oil on water is subjected to<sup class="xref">17</sup>. Other, more sophisticated weathering methods can also be used to provide weathered crude oil samples, such as the circulating flume described by Brandvik and Faksness<sup class="xref">35</sup>. The advantage of the presented methods is that they require simple equipment and can be easily conducted in a laboratory environment. The result...

<p class="jove_content"><em>In situ</em> burning of spilled crude oil on water is a marine oil spill response method that removes the spilled oil from the water surface by burning it and converting it to soot and gaseous combustion products. This response method was successfully applied during the Exxon Valdez<sup class="xref">1</sup> and Deepwater Horizon<sup class="xref">2</sup> oil spills and is regularly mentioned as a potential oil spill response method for the Arctic<sup class="xref">3</sup><sup>,</sup><sup class="xref">4</sup><sup>,</sup><sup class="xref">5</sup><sup>,</sup><sup class="xref">6</sup>. Two of the key parameters that determine whether <em>in situ</em> burning of oil will be successful as a spill response method are the flammability and the burning efficiency of the oil. The first parameter, flammability, describes how easily a fuel can be ignited and can lead to flame spreading over the fuel surface to result in a fully developed fire. The second parameter, burning efficiency, expresses the amount of the oil (in wt%) that is effectively removed from the water surface by the fire. It is thus relevant to understand the flammability and the expected burning efficiency of different crude oils under <em>in situ</em> burning conditions.</p>
<p class="jove_content">The ignition of oil slicks on water for <em>in situ</em> burning purposes is commonly addressed as a practical problem, with qualitative discussions on ignition systems<sup class="xref">5</sup><sup>,</sup><sup class="xref">7</sup><sup>,</sup><sup class="xref">8</sup><sup>,</sup><sup class="xref">9</sup>. The practical approach to the ignition of spilled oil as a binary problem, and labelling oils either &#34;ignitable&#34; or &#34;not ignitable&#34; (<em>e.g. </em>Brandvik, Fritt-Rasmussen, <em>et al</em>.<sup class="xref">10</sup>) is, however, incorrect from a fundamental point of view. In theory, any fuel can be ignited given an appropriate ignition source. It is therefore relevant to quantify the ignition requirements for a wide range of different crude oil types to better understand the properties of a crude oil that would label it as &#34;not ignitable&#34;. For this purpose, the developed method can be used to study the ignition delay time of an oil as a function of the incident heat flux, the critical heat flux of the oil and its thermal inertia, <em>i.e.</em> how difficult it is to heat up the oil.</p>
<p class="jove_content">In a previous study, we postulated that the main parameter that governs the burning efficiency is the heat feedback to the fuel surface<sup class="xref">11</sup>, which is a function of the pool diameter. The theory explains the apparent pool size dependency of the burning efficiency based on laboratory studies reporting low burning efficiencies (32-80%)<sup class="xref">8</sup><sup>,</sup><sup class="xref">12</sup><sup>,</sup><sup class="xref">13</sup> and large scale studies (pool diameter &#8805;2 m) reporting high burning efficiencies (90-99%)<sup class="xref">14</sup><sup>,</sup><sup class="xref">15</sup><sup>,</sup><sup class="xref">16</sup>. The method discussed herein was designed to test the proposed theory. By subjecting small scale laboratory experiments to a constant external heat flux, the higher heat feedback for large scale pool fires can be simulated under controlled laboratory conditions. As such, the developed method allows studying the burning efficiency effectively as a function of the diameter by varying the external heat flux.</p>
<p class="jove_content">In addition to an external heat flux to simulate the larger scale of <em>in situ</em> burning operations, the experimental setups feature cooling of the oil slick by a cold-water flow, simulating the cooling effect of the sea current. The discussed method is furthermore compatible with both fresh and weathered crude oils. The weathering of crude oil describes the physical and chemical process that affect a crude oil once it is spilled on water, such as losses of its volatile components and mixing with water to form water-in-oil emulsions (<em>e.g.,</em> AMAP<sup class="xref">17</sup>). Evaporation and emulsification are two of the main weathering processes that affect the flammability of crude oils<sup class="xref">18</sup> and protocols for simulating these weathering processes are therefore included in the discussed method.</p>
<p class="jove_content">Herein, we present a novel laboratory method that determines the flammability and burning efficiency of crude oil under conditions that simulate <em>in situ</em> burning operations on sea. Previous studies on the flammability and burning efficiency of crude oils featured both comparable and different methods. The flammability of fresh and weathered crude oils as a function of an external heat flux was studied on water<sup class="xref">19</sup> and under Arctic temperatures<sup class="xref">20</sup>. Burning efficiency studies typically focus on different types of fresh and weathered crude oils and environmental conditions at a fixed scale (<em>e.g.,</em> Fritt-Rasmussen, <em>et al</em>.<sup class="xref">8</sup><sup> </sup>Bech, Sveum, <em>et al</em>.<sup class="xref">21</sup>). A recent study on the burning of crude oils contained by chemical herders is, to the knowledge of the authors, the first to study the burning efficiency for small, intermediate, and large scale experiments under similar conditions<sup class="xref">13</sup>. Large scale experiments are, however, not readily available for parametric studies due to the extensive amount of time and resources required for conducting such experiments. The main advantage of the presented method over the previously mentioned studies is that it allows for simultaneously studying both the flammability and burning efficiency of crude oil under semi-realistic conditions. The combination of studying these two parameters for crude oils as a function of both different oil types and the (simulated) pool diameter through easily repeatable experiments was previously unfeasible in practice.</p>

<table><tbody><tr><td>DUC Crude Oil</td><td>Maersk</td><td>N/A</td><td>Light crude oil with r = 0.853 g/ml and h = 6.750 mPa*s.</td></tr><tr><td>Grane Crude Oil</td><td>Statoil</td><td>N/A</td><td>Heavy crude oil with r = 0.925 g/ml and h = 133.6 mPa*s.</td></tr><tr><td>SVM 3000 Stabinger Viscometer</td><td>Anton Paar</td><td>C18IP007EN-P</td><td>Viscosity and density meter for the fresh and weathered crude oils.</td></tr><tr><td>Laboshake RO500</td><td>Gerhardt</td><td>11-0002</td><td>Rotary shaking table for emulsifying water and oil mixtures.</td></tr><tr><td>Jebao Wave Maker RW-4</td><td>Jebao</td><td>N/A</td><td>Propeller (flow of 500-4000 L/h) used in the COFA setup to generate a current.</td></tr><tr><td>Aquabee UP 3000</td><td>Aquabee</td><td>UP 3000</td><td>Aquarium pump for cooling of heat flux gauge.</td></tr><tr><td>Adventurer Precision Electronic Balance</td><td>OHAUS</td><td>AX5205</td><td>Load scale used to weigh the oil for the COFA experiments and in the custom-made cone sample holder for the cone setup.</td></tr><tr><td>3M Oil Sorbent Pads</td><td>VWR</td><td>MMMAHP156</td><td>Hydrophobic absorption pads used to collect oil residues to determine the burning efficiency of the fire.</td></tr><tr><td>Mass Loss Calorimeter</td><td>Fire Testing Technology (FTT)</td><td>B11325-650-1-1608</td><td>A custom-made, circular holder was used for the testing of crude oil rather than the standard square sample holder. Includes a heat flux gauge with a range up to 100 kW/m&lt;sup&gt;2&lt;/sup&gt;.</td></tr><tr><td>34972A Data Acquisition / Data Logger Switch Unit</td><td>RS Components Ltd.</td><td>702-7958</td><td>Produced by Keysight Technologies. Operated by Keysight benchLink data logger 3 software and equipped with a 20-channel multiplexer.</td></tr><tr><td>Keysight Technologies 34901A 20-channel multiplexer</td><td>RS Components Ltd.</td><td>702-7939</td><td>Produced by Keysight Technologies.</td></tr><tr><td>Bellows-Sealed Valve</td><td>Swagelok</td><td>SS-1GS6MM</td><td>Toggle valve to open/close the water in- and outlet of the custom-made cone sample holder for the cone setup.</td></tr><tr><td>Kronos 50 Peristaltic Pump</td><td>SEKO</td><td>KRFM0210M6000</td><td>Peristaltic pump used to cool the custom-made cone sample holder for the cone setup.</td></tr><tr><td>ARCTIC A28 Refrigerated Circulater</td><td>ThermoFisher Scientific</td><td>152-5281</td><td>Water cooling reservoir used to cool the cooling water that flows through the custom-made cone sample holder for the cone setup. Includes a SC 100 Immersion Circulator controller.</td></tr><tr><td>Gas Analysis Instrumentation Console with Duct Insert</td><td>Fire Testing Technology (FTT)</td><td>B11328-650-1-1609</td><td>Gas analyzer for O&lt;sub&gt;2&lt;/sub&gt;, CO&lt;sub&gt;2&lt;/sub&gt; and CO. Uses a 34972A Data Acquisition / Data Logger Switch Unit.</td></tr><tr><td>Ceramic &amp;amp; Stainless Steel 2.5mm Electrode</td><td>Fire Testing Technology (FTT)</td><td>M015-4</td><td>Spark igniter from the Mass Loss Calorimeter. Used in the COFA setup to measure the surface temperature upon ignition.</td></tr><tr><td>Infrared Emitter-Module M110/348</td><td>Heraeus</td><td>80046199</td><td>Original Infrared heaters on which the new design with a water-cooled holder for the heating elements was based. Includes two short wave twin tube emitters (09751751). Operated by a type CB1x25 P power controller.</td></tr><tr><td>Power Controller Heratron&amp;nbsp;</td><td>Heraeus</td><td>80055836</td><td>Type CB1x25 P power controller for the infrared heaters.</td></tr></tbody></table>

experimental procedure for laboratory studies of <em>in situ</em> burning : flammability and burning efficiency of crude oil

<p class="jove_content">A new method for the simultaneous study of the flammability and burning efficiency of fresh and weathered crude oil through two experimental laboratory setups is presented. The experiments are easily repeatable compared to operational scale experiments (pool diameter &#8805;2 m), while still featuring quite realistic <em>in situ</em> burning conditions of crude oil on water. Experimental conditions include a flowing water sub-layer that cools the oil slick and an external heat flux (up to 50 kW/m<sup>2</sup>) that simulates the higher heat feedback to the fuel surface in operational scale crude oil pool fires. These conditions enable a controlled laboratory study of the burning efficiency of crude oil pool fires that are equivalent to operational scale experiments. The method also provides quantitative data on the requirements for igniting crude oils in terms of the critical heat flux, ignition delay time as a function of the incident heat flux, the surface temperature upon ignition, and the thermal inertia. This type of data can be used to determine the required strength and duration of an ignition source to ignite a certain type of fresh or weathered crude oil. The main limitation of the method is that the cooling effect of the flowing water sub-layer on the burning crude oil as a function of the external heat flux has not been fully quantified. Experimental results clearly showed that the flowing water sub-layer does improve how representative this setup is of <em>in situ</em> burning conditions, but to what extent this representation is accurate is currently uncertain. The method nevertheless features the most realistic <em>in situ</em> burning laboratory conditions currently available for simultaneously studying the flammability and burning efficiency of crude oil on water.</p>

<p class="jove_content" fo:keep-together.within-page="1"><strong class="xfig">Figure 5</strong> shows the evaporation curve of a light crude oil that was evaporated over multiple days to a loss of 30 wt% using the method described in step 2. The figure clearly shows that after the first day (19 h) of evaporative weathering, the evaporation rate is reduced significantly, which allows for pauses as mentioned in the protocol.</p>
<p class="jove_content" fo:keep-together.within-page="1"><strong class="xfig">Figure 6</strong> shows the ignition dela...

Watch this Scientific Journal Video about Experimental Procedure for Laboratory Studies of In Situ Burning : Flammability and Burning Efficiency of Crude Oil at JoVE.com

Experimental Procedure for Laboratory Studies of In Situ Burning : Flammability and Burning Efficiency of Crude Oil

<p class="jove_content">Here, we present a protocol to simultaneously study the flammability and burning efficiency of fresh and weathered crude oil under conditions that simulate <em>in situ</em> burning operations on the sea.</p>

Experimental Procedure for Laboratory Studies of <em>In Situ</em> Burning : Flammability and Burning Efficiency of Crude Oil

A new method for the simultaneous study of the flammability and burning efficiency of fresh and weathered crude oil through two experimental laboratory ...

experimental-procedure-for-laboratory-studies-situ-burning

Universidad de Cartagena UDEC

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12.4K Views.  Technical University of Denmark. Here, we present a protocol to simultaneously study the flammability and burning efficiency of fresh and weathered crude oil under conditions that simulate in situ burning operations on the sea.

Video: Experimental Procedure for Laboratory Studies of In Situ Burning : Flammability and Burning Efficiency of Crude Oil

Basic Organic Chemistry Techniques

<p><strong>Glassware in Organic Chemistry</strong></p>
<p>There are standard pieces of glassware that are used in the organic chemistry lab. Beakers and Erlenmeyer flasks are typically used for simple mixing or to hold solvents but they should not be used to measure volume, unless only an approximate volume is needed. Glassware can be divided into the following categories:</p>
<ol>
	<li style="font-size:17px">Volumetric Glassware &#8211; This includes glassware such as graduated cylinders, volumetric glass pipettes, and volumetric flasks. The purpose of these items is to measure or dispense a precise volume of a substance. A graduated cylinder is generally used to measure volumes in an organic lab. The graduated cylinder has a long cylindrical shape with volume markings on the side. It is essential to use the smallest graduated cylinder possible for the volume needed in order to minimize error. For example, a 25-mL graduated cylinder is adequate to measure 20 mL of reagent, but it is not accurate to measure a smaller volume, like 5 mL. However, do not use a 25-mL graduated cylinder to measure 100 mL by measuring four 25-mL volumes; it is better to use the 100-mL graduated cylinder.</li>
	<li style="font-size:17px">Reaction Containment &#8211; These specialized pieces can be used to house an organic chemical reaction. Round-bottom flasks are an example of this glassware. Unlike Erlenmeyer flasks, round-bottom flasks provide more surface area and therefore provide more uniform heating or cooling. Round-bottom flasks are used to perform reactions under high heat or vacuum because their round shape is more resistant to cracking. In this category are also specialized glassware known as condensers, which are used to collect gaseous vapors and condense them back into the liquid phase to be collected.</li>
	<li style="font-size:17px">Filtration &#8211; These pieces of glassware are mainly used to help isolate precipitates out of a reaction mixture. To isolate solid precipitates, a filtration apparatus is required. The simplest setup utilizes a glass funnel attached to an Erlenmeyer flask. Inside the funnel is a piece of filter paper. The reaction mixture containing the solid is poured into the funnel, and gravity will pull the liquid down into the flask, leaving behind the solid. This is known as gravity filtration. However, this setup may require a long period of time to filter the solid. A vacuum filtration setup replaces the Erlenmeyer flask with a vacuum flask with a side arm and the glass funnel with a porcelain filter funnel known as a B&#252;chner funnel. This side arm is attached to a vacuum source. Like before, the reaction mixture is poured into the filter funnel and the filtration is aided by force from the vacuum.</li>
	<li style="font-size:17px">Separation &#8211; These specialized flasks or funnels are used mainly for liquid-liquid phase extractions, which is a technique that allows for the separation of products by using solvents with different polarities or hydrophobicities. These immiscible liquids will form a heterogeneous solution that separates into two phases. Separatory funnels have a valve known as a stopcock at the bottom, allowing for separation of the phases by pouring them into a new container.</li>
	<li style="font-size:17px">Transport &#8211; This glassware mostly consists of bottles or vials with a corresponding cap. This glassware is used primarily to transport potentially hazardous material safely.</li>
	<li style="font-size:17px">General use &#8211; This category is comprised of glassware such as beakers, Erlenmeyer flasks, glass rods, and any other miscellaneous pieces.</li>
</ol>
<p><strong>Weighing Organic Reagents</strong></p>
<p>Organic reagents can come in multiple forms, and it is important to practice good lab technique when obtaining these reagents for use in experiments. Always review a reagent&#39;s MSDS to determine potential hazards when working with it. Solid reagents should be measured out using weighing boats or weighing paper and the appropriate type of balance.</p>
<p>If a precise measurement is required, use an analytical balance. If a large amount of reagent is to be used, use a top-loading balance. Place a weighing boat or weighing paper on the balance and push the &#8220;tare&#8221; button. The tare feature will null the mass of the weighing paper. Always use spatulas to transfer solid reagents from the supply to the weighing boat. Never reuse the same spatula for different reagents as this can contaminate the stock reagents. And never return excess reagent to the stock bottle. Instead, discard it in the appropriate way as instructed.</p>
<p>When transferring the solid to the appropriate vessel, use a small funnel to carefully pour the solid inside. If any solid remains, use a small amount of the solvent to be used on the weighing boat and transfer it into the flask.</p>
<p>Organic liquids can be measured by using volumetric glassware, such as a graduated cylinder. Calculate the volume of the liquid using its density, then tare the reaction flask on the balance. Use a pipet or graduated cylinder to transfer the volume directly to the reaction flask. Follow the guidelines for the specific type of glassware. Never reuse the same piece of glassware for multiple reagents and never return excess reagent to the liquid stock bottles. For liquids, c</p>
<p><strong>Heating Organic Reactions</strong></p>
<p>Sometimes heat is required to enable an organic chemical reaction to occur. In the general lab setting, heat is commonly applied using a Bunsen burner with a direct gas flame. In organic chemistry labs, an open flame from a Bunsen burner can create a dangerous situation. Organic reagents, particularly solvents, are highly combustible and some form vapors with relative ease. For that reason, Bunsen burners are not used in organic chemistry labs.</p>
<p>Instead, heating baths, hotplates, or mantles are used to provide an indirect source of heat. Hotplates with magnetic stirring functionality are used to heat beakers and Erlenmeyer flasks. Heating mantles are designed to safely heat a round-bottom flask with varying volumes. Water baths are used when the temperature of the reaction does not need to exceed 100 &#176;C. A reaction in glassware is immersed in a water bath that is heated by a hot plate. The temperature is modulated to the appropriate range. If the required temperature needs to exceed 100 &#176;C but not 250 &#176;C, a silicone mantle can be used. If the temperature must exceed 250 &#176;C, a sand bath can be used.</p>
<p>Many reactions require being heated to a certain temperature for long periods of time in order for it to proceed. However, if a reaction is heated for a long period of time, the solvent may evaporate, causing a loss of reaction solution. Instead, a reflux setup is often used, which uses a round-bottom flask containing a solvent. The boiling point of the solvent overlaps with the optimal temperature of the reaction. The round-bottom flask is clamped to a stand, and a condenser is fitted onto the flask. Cold water flows through the condenser from the bottom arm to the top arm while the mixture is heated and stirred. As the mixture is heated, the solvent evaporates and then condenses back into the flask, preserving the reaction volume.</p>

Podstawowe techniki chemii organicznej

Glassware in Organic Chemistry
There are standard pieces of glassware that are used in the organic chemistry lab. Beakers and Erlenmeyer flasks are ...

JoVE Lab Manual

Boiling Points

<p>Source: Lara Al Hariri at the University of Massachusetts Amherst, MA, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Preparation of the Laboratory<button class="expand">Expand</button>
	<p><em>Here, we show the laboratory preparation for 10 students working in pairs, with some excess. Please adjust quantities as needed.</em></p>
	<ul class="lab-items">
		<li data-sub-note-item="1-2">
		<div class="lab-step">Put on the necessary personal protective equipment, including a lab coat, chemical splash goggles, and gloves.</div>
		</li>
		<li data-sub-note-item="1-3">
		<div class="lab-step">The students will need to use both acetone and ethanol in their experiment. Label a glass bottle with the solvent name, and then pour a smaller volume of solvent from the stock bottle into the glass bottle, ensuring that there is enough for each group to have about 1 mL. Do the same for the other solvent and then place these bottles in a communal hood.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Set out the following glassware and equipment at each student lab station (we suggest that students work in pairs):
		<table align="center" style="border-collapse: collapse; font-size: 17px; line-height: 24px;">
			<tbody>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Lab stand</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Hotplate</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Lab jack</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Rubber band</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Medium 3-prong clamp</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;3-4&#160;&#160;&#160;&#160;Glass capillary tubes</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Pipette bulb</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;2&#160;&#160;&#160;&#160;1-mL volumetric pipettes</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;2&#160;&#160;&#160;&#160;Glass test tubes</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;250-mL beaker</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;25-mL beaker</td>
				</tr>
				<tr>
					<td style="border: 1px solid; padding: 0px; ">&#160;1&#160;&#160;&#160;&#160;Digital thermometer</td>
				</tr>
			</tbody>
		</table>
		</div>
		</li>
	</ul>
	</li>
</ol>

Determination of Boiling Points by Capillary Method - Prep

Temperatury wrzenia

Source: Lara Al Hariri at the University of Massachusetts Amherst, MA, USA

	Preparation of the LaboratoryExpand
	Here, we show the laboratory preparation ...

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Enthalpy of Reaction

Enthalpy of Reaction and Measurement of Heat by Calorimeter - procedure

Entalpia reakcji

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Collecting Data for Calculating the Heat Capacity of a CalorimeterExpand
	This experiment will ...

Metal Flame Emission

<p>Source: Smaa Koraym at Johns Hopkins University, MD, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Metal Flame Emission Testing<button class="expand">Expand</button>
	<p>In this lab, you will excite the electrons of six metal chloride salts with heat from a flame and measure the wavelength of light emitted by the relaxing electrons. The emitted light is in the visible spectrum, so you will see different colored flames for the different metals.</p>
	<p>At the end of the lab, you will measure the emission spectrum of a sparkler and use the data you collected from the metal salts to identify the metals in the sparkler. To help with this process, make a table in your lab notebook to record the wavelengths emitted from ambient light, the salts, and the sparkler.</p>
	<h4><strong>Table 1: Observed Wavelengths</strong></h4>
	<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
		<tbody>
			<tr>
				<td style="text-align: center;"><strong>Run #</strong></td>
				<td style="text-align: center;"><strong>Source</strong></td>
				<td style="text-align: center;"><strong>Recorded wavelength(s)</strong></td>
			</tr>
			<tr>
				<td style="text-align: center;">1</td>
				<td style="text-align: center;">Room lights</td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">2</td>
				<td style="text-align: center;">NaCl</td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">3</td>
				<td style="text-align: center;">LiCl</td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">4</td>
				<td style="text-align: center;">KCl</td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">5</td>
				<td style="text-align: center;">SrCl<sub>2</sub></td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">6</td>
				<td style="text-align: center;">BaCl<sub>2</sub></td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">7</td>
				<td style="text-align: center;">CuCl<sub>2</sub></td>
				<td></td>
			</tr>
			<tr>
				<td style="text-align: center;">8</td>
				<td style="text-align: center;">Sparkler</td>
				<td></td>
			</tr>
		</tbody>
	</table>
	<p><a href="https://jove.unicartagenaproxy.elogim.com/CDNSource/lm/labs/48/Table_1._Observed_Wavelengths.xlsx" target="_blank">Click Here to download Table 1</a></p>
	<p>During this lab, you will hold a salt-coated applicator at the edge of a Bunsen burner flame to excite the metal salts. If the applicator catches fire, immediately quench it in a beaker of water. For excitation, you will hold a detector near the flame and the sparkler to measure the wavelengths of the emitted light. Keep a safe distance to protect yourself and the detector. As some tasks are performed simultaneously, we suggest that you work in groups of four with each student completing tasks as needed.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-4">
		<div class="lab-step">Put on a lab coat, safety glasses, and nitrile gloves.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Set up the Bunsen burner in the fume hood.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Fill a 400-mL beaker with tap water and bring it to the hood. Place the salts, applicators, and tap water within easy reach on one side of the Bunsen burner.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Turn on the hand-held spectrophotometer and familiarize yourself with its components.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Create a new experiment and configure the spectrometer to measure emission intensity. Set the sample time to 200 ms and the number of readings at a given wavelength to 1. Record the settings and the experiment name in your lab notebooks.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Measure the spectrum of the room lights. Have one or two students hold the optical detector as close to the lights as possible without disconnecting the cables. Once ready, have a different student start the spectrometer. The spectrum should be clear, with minimal noise and no off-scale peaks. <strong>Note: </strong>If you have trouble, hold the probe in a nearly closed drawer or box to shield it from sunlight while pointing it at the room lights.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Immediately capture the spectrum when it looks good. Confirm that you have a high-quality spectrum before saving it. Record the wavelengths of the peaks in your data table.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">Measure the emission spectra of the metal salts. Ignite the Bunsen burner and adjust the collar until the flame distinctly separates into an inner and outer flame.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Bring the spectrometer to the hood and arrange the cables so that the detector can be held about one inch from the flame.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Have one student prepare the spectrometer for the run. This student should have a clear view of the burner so they can begin acquiring data as soon as the salt enters the flame. Then, have another student hold the detector no closer than one inch from the flame. <strong>Note: </strong>Any closer risks damaging the detector. But you won&#39;t get a clear spectrum if the detector is too far away.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">Have a different student take one of the applicators from the beaker of water and dip it into the tube of NaCl to coat the wet cotton with the salt. Then, carefully insert the salt-coated applicator about 1 mm into the outer flame, which will change color.</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Start the spectrometer when the applicator enters the flame.<strong> Note: </strong>If the peak intensities are off-scale, adjust the detector position until all peaks are within detection limits. If the flame color change is hard to see, pick up more salt on the same applicator and try again until you see an intense color. If the spectrum is noisy or weak, try pointing the detector at a different part of the flame.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">When you see a good spectrum, capture and save it. Everyone should review the spectrum to ensure that it is of good quality. Write down the emission wavelengths in your table.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Submerge the NaCl applicator in your wastewater beaker. Always use a different applicator for each salt.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">Follow the same procedure to test the remaining five salts, being careful to avoid cross-contamination between the salts. Once you have tested the last salt and recorded the wavelengths, set up data collection for the sparkler.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">At the instructor&#39;s hood, light the sparkler with the Bunsen burner and place it handle down in the Erlenmeyer flask. Remember, the sparks may be very hot. Turn off the gas to extinguish the Bunsen burner.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">As one student holds the detector close to the sparkler, have another student start data collection. Position the detector to get as many peaks in scale as possible without losing the less intense peaks.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">Capture and save the spectrum once it looks good. Remember to write down the wavelengths in your table. <strong>Note: </strong>If the sparkler is long-lived, collect a second spectrum and either choose the best one or keep them both for the analysis.</div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">Let the sparkler burn out in the hood while you send the collected data to everyone in the group and shut down the data acquisition system.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Bring the copper, barium, and strontium tubes to the waste hood and thoroughly rinse the tubes with deionized water into the designated waste container.</div>
		</li>
		<li data-sub-note-item="1-24">
		<div class="lab-step">Flush the sodium, potassium, and lithium salts down the drain and rinse the remaining test tubes. Put away the test tubes and the other equipment.</div>
		</li>
		<li data-sub-note-item="1-25">
		<div class="lab-step">Once the ashes and sparkler handle have cooled, dump them in the trash.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Results<button class="expand">Expand</button>
	<ul class="lab-items">
		<li data-sub-note-item="2-1">
		<div class="lab-step">First, plot the data for each run with intensity on the y-axis and wavelength on the x-axis.</div>
		</li>
		<li data-sub-note-item="2-2">
		<div class="lab-step">Compare the sparkler spectrum to the background spectrum from the room lights. Identify which small peaks may be from the room lights.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">Compare the metal spectra to the sparkler spectrum. Sodium appears to be the source of the peak at about 589 nm. There are no peaks matching the lithium spectrum, but potassium matches the large peak at 770 nm.</div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">The sparkler spectrum doesn&#39;t seem to have strontium peaks. However, barium is a good match for several peaks in the sparkler spectrum. Lastly, no copper seems to be present in the sparkler. Thus, we conclude that the sparkler was burning sodium, potassium, and barium when the spectrum was acquired.</div>
		</li>
	</ul>
	</li>
</ol>

Emisja płomienia metalu

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Metal Flame Emission TestingExpand
	In this lab, you will excite the electrons of six metal ...

Beer's Law

Beer-Lambert Law and Equilibrium Constant Determination - Procedure

Prawo piwa

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Lab Setup for Beer&#8217;s LawExpand
	In this lab, you will combine aqueous solutions of FeCl3 ...

Melting Points

<p>Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Determining the Melting Points of Naphthalene, Urea, and an Unknown Mixture<button class="expand">Expand</button>
	<p>In this experiment, you will measure the melting point range of two known substances, naphthalene and urea, by observing the melting phenomenon during heating. You&#39;ll then analyze a mixture of urea and an unknown substance to observe how the unknown impurity affects the melting point range.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-2">
		<div class="lab-step">Put on a lab coat, splash-proof safety glasses, and nitrile gloves.</div>
		</li>
		<li data-sub-note-item="1-3">
		<div class="lab-step">Weigh ~1 mg of naphthalene using the analytical balance, and carefully, bring it back to your bench.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Transfer the naphthalene onto a watch glass, and then crush it using the metal spatula until it becomes a fine powder.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Carefully pick up one capillary tube and tap the open end on the powder to force some of the solid into the tube.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Obtain a long glass tube from the common bench and hold it upright over your bench. Pick up the capillary with the open end upward and then drop it through the glass tube. Allow the capillary to bounce off the benchtop to pack the solid at the bottom.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Retrieve the capillary and tap its open end on the naphthalene powder again to force more of it into the capillary. Continue loading naphthalene into the capillary and dropping it through the glass tube until 1 &#8211; 2 mL of powder is packed at the bottom of the capillary.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Use a rubber band to attach the capillary to a digital thermometer, with the bottom of the capillary just above the bottom of the thermometer. <strong>Note:</strong> Make sure that the rubber band is at least 8 &#8211; 9 cm above the solid in the capillary.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Set up a stirring hotplate and a lab stand in a fume hood and clamp the thermometer above the hotplate.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Place the provided mineral oil bath on the hotplate and add a magnetic stir bar. Start stirring the bath at a moderate speed over low heat.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">Lower the thermometer and capillary setup into the oil bath until the sample is about 5 cm deep in the bath. <strong>Note:</strong> Make sure that the rubber band is above the mineral oil.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Increase the hotplate temperature to 60&#176;C, which is about 20&#176; below the melting point of naphthalene in the literature.<strong> Note:</strong> It will take about 10 min for the entire oil bath to reach the same temperature as the hotplate.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Once the bath reaches 60&#176;C, heat it to 75&#176;C at a rate of 5&#176;C/min. When the bath is close to the melting point of naphthalene (80&#176;C), heat the bath by 1 &#8211; 2 &#176;C/min while carefully observing the solid in the capillary.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">At the first drop of liquid in the capillary, record the temperature of the oil bath. Keep watching the capillary tube as you slowly increase the temperature. Record the temperature when the last piece of solid melts.
		<h4><strong>Table 1: Melting Points of Naphthalene, Urea, and an Unknown Mixture</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td></td>
					<td colspan="2" style="text-align: center;"><strong>Melting point temperature (&#176;C)</strong></td>
				</tr>
				<tr>
					<td><strong>Substance</strong></td>
					<td style="text-align: center;"><strong>Start</strong></td>
					<td style="text-align: center;"><strong>End</strong></td>
				</tr>
				<tr>
					<td>Napthalene</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Urea</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Urea + Unknown (trial 1)</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Urea + Unknown (trial 2)</td>
					<td></td>
					<td></td>
				</tr>
			</tbody>
		</table>
		<a href="https://jove.unicartagenaproxy.elogim.com/CDNSource/lm/labs/66/Table_1._Melting_points_of_naphthalene,_urea,_and_an_unknown_mixture.xlsx" target="_blank">Click Here to download Table 1</a></div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Carefully remove the capillary and thermometer from the oil bath and set them aside to cool.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">Weigh roughly 1 mg of urea and transfer it to a clean watch glass. Crush the urea to a powder. Load the powder into a capillary tube as before.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Attach the capillary to the thermometer with the rubber band. Heat the oil bath to 110&#176;C, which is about 20&#176; below the reported melting point of 132&#176;C for urea.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">Insert the thermometer and capillary tube into the oil bath. Heat the bath to about 125&#176;C at 5&#176;C/min while watching the capillary.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">When the bath reaches 125&#176;C, heat the bath by 1 &#8211; 2&#176;C /min. Record the temperature when the first drop of liquid appears and when the last bit of solid melts.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">Turn off the hotplate and remove the capillary and thermometer from the oil bath to allow them to cool.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">Test the sample of urea mixed with an unknown impurity, which was prepared by your instructor. Perform two runs of this sample, so weigh 2 mg of the sample on the balance and transfer it to a watch glass.</div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">Crush the sample to powder and load two capillaries by tapping them on the powder and dropping them through the glass tube like before.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Once the oil bath has cooled to at least 80&#176;C, turn on the stir motor and set the hotplate to 80&#176;C. Attach one of the loaded capillaries to the thermometer and clamp them in the oil bath.</div>
		</li>
		<li data-sub-note-item="1-24">
		<div class="lab-step">In the first test run, increase the temperature by 10&#176;C/min until the sample has melted to determine the rough melting point range. Record the temperature when you see the first drop of liquid form and the last drop of liquid form to determine the rough melting point range.</div>
		</li>
		<li data-sub-note-item="1-25">
		<div class="lab-step">Turn off the hotplate and allow it to cool. Once the oil bath has cooled to at least 80&#176;C, attach the second sample to the thermometer and clamp them in the bath. Turn the stir motor back on and set the hotplate to 80&#176;C.</div>
		</li>
		<li data-sub-note-item="1-26">
		<div class="lab-step">For the second test, heat the bath by 5&#176;C/min until you are close to the rough melting point range, and then continue heating by 1 &#8211; 2&#176;C/min to accurately capture the melting point range.</div>
		</li>
		<li data-sub-note-item="1-27">
		<div class="lab-step">When you have finished measuring the melting point of the urea mixed with the unknown substance, turn off the hotplate and detach the capillary tube from the thermometer. Dispose of your capillary tubes in the glass waste container.</div>
		</li>
		<li data-sub-note-item="1-28">
		<div class="lab-step">Return the mineral oil to your instructor, and clean all of your glassware using detergent and water.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Results<button class="expand">Expand</button>
	<ul class="lab-items">
		<li data-sub-note-item="2-1">
		<div class="lab-step">First, look at the melting point range of naphthalene. These differences may be caused by experimental errors, such as heating the sample too quickly, or by impurities in the sample.</div>
		</li>
		<li data-sub-note-item="2-2">
		<div class="lab-step">Next, check the results for the pure urea sample. Why is urea&#39;s melting point so much higher than naphthalene&#39;s? Looking at the structure of naphthalene, the intermolecular forces must be primarily London dispersion forces. Urea is capable of hydrogen bonding, so the intermolecular forces in solid urea are much stronger than the forces in solid naphthalene.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">Finally, look at the results from the urea sample with the impurity. The melting point range should be broader and lower than the range for pure urea because of freezing point depression. As expected, the melting point range obtained was 127 &#8211; 130&#176;C, which is lower than the range for pure urea.</div>
		</li>
	</ul>
	</li>
</ol>

Determination of Melting Points - Procedure

Temperatury topnienia

Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA

	Determining the Melting Points of Naphthalene, Urea, and ...

Simple Distillation

<p>Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Simple Distillation<button class="expand">Expand</button>
	<p>In this lab, you will use simple distillation to separate a mixture of cyclohexane and toluene.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-2">
		<div class="lab-step">Before you start the lab, put on the appropriate personal protective equipment, including a lab coat, safety goggles, and gloves. This experiment must be conducted in a hood.</div>
		</li>
		<li data-sub-note-item="1-3">
		<div class="lab-step">Assemble the distillation apparatus. Refer to the example set up that has been prepared by your instructor.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Then, set up the two stands next to each other in the hood. Place the magnetic stirrer on the base of one of the stands.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Set the heating mantle on top of the magnetic stirrer, and then plug it into the temperature controller.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Add 5 &#8211; 10 mL of sand to the heating mantle. This will allow more homogeneous heating of the round-bottom flask. Clamp the round-bottom flask to the stand above the heating mantle.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Now, obtain cyclohexane and toluene from your instructor. Measure 2 mL of cyclohexane using a volumetric pipette and dispense it into the round-bottom flask.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Then, use a clean volumetric pipette to measure 2 mL of toluene and add it to the flask.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Carefully insert a thermometer into an adapter by gently pushing and twisting it through the top.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Lightly grease the adapter with vacuum grease and insert it into the distilling head. Make sure that the thermometer bulb is below the bend of the distilling head. Then, lightly grease the joints of the distilling head.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">Add a stir bar to the round-bottom flask and insert the distilling head into the round-bottom flask.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Now, clamp the condenser to the second stand with it oriented diagonally toward the side joint of the distilling head.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Connect one piece of tubing to the tap water faucet in the hood, and attach the other end to the inlet port of the condenser, which is located farthest from the distilling head.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">Attach the second tubing to the outlet port, which is located closest to the distilling head, and place the other end of the tubing into the drain.</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Connect the condenser to the distilling head. Then, lightly grease the joint of the condenser and attach the connecting tube. Place a 10-mL graduated cylinder below the outlet of the tube.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">Gently lower the setup until the round-bottom flask is seated in the sand in the heating mantle.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Double-check all of the connections on your setup to make sure that they are tight and oriented correctly. Secure each joint with a plastic clip.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">Now, slowly turn on the flow of water to the condenser. <strong>Note:</strong> Be careful not to turn on the water too quickly. If the water pressure is high, the tubing may pop off the condenser.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">Turn the magnetic stirrer to the lowest setting, and set the temperature controller to heat the mantle to just above 90 &#176;C.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">Once bubbles start forming in the liquid mixture, adjust the heat until the distillation rate is about 2 drops/min. You should also see drops forming on the thermometer bulb.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">Record the temperature after every 2 drops that fall into the graduated cylinder or every minute.
		<h4><strong>Table 1: Distillation of toluene and cyclohexane</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td><strong>Time (min) </strong></td>
					<td><strong>Distilled volume (mL) </strong></td>
					<td><strong>Temperature (&#176;C) </strong></td>
				</tr>
				<tr>
					<td style="text-align: center;">1</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">2</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">3</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">4</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">5</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">6</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">7</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">8</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">9</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">10</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">11</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">12</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">13</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">14</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
				<tr>
					<td style="text-align: center;">15</td>
					<td style="text-align: center;"></td>
					<td style="text-align: center;"></td>
				</tr>
			</tbody>
		</table>
		<a href="https://jove.unicartagenaproxy.elogim.com/CDNSource/lm/labs/60/Table_1._Distillation_of_toluene_and_cyclohexane.xlsx" target="_blank">Click Here to download Table 1</a></div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">When there is about 0.5 mL of the mixture remaining in the flask, which will look like a thin layer of liquid, turn off the heat and gently lift the glassware setup from the heating mantle. <strong>Note:</strong> Never heat the mixture until the flask is dry as this may cause an explosion.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Remove the stir plate with the heating mantle and set it aside.</div>
		</li>
		<li data-sub-note-item="1-24">
		<div class="lab-step">Then, turn off the water to the condenser and allow the setup to cool completely. When it is cool, carefully disassemble the glassware.</div>
		</li>
		<li data-sub-note-item="1-25">
		<div class="lab-step">Dispose of all solutions in the non-halogenated organic waste container. Clean your glassware with acetone followed by detergent and deionized water.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Results<button class="expand">Expand</button>
	<ul class="lab-items">
		<li data-sub-note-item="2-1">
		<div class="lab-step">Plot the dew point temperature versus the distilled volume during the experiment. We see that drops start to fall into the collection vessel at ~ 81 &#176;C, which is the boiling point of cyclohexane. As the distillation progresses, the temperature increases to almost 111 &#176;C, which is the boiling point of toluene.</div>
		</li>
		<li data-sub-note-item="2-2">
		<div class="lab-step">Early in the distillation, the vapor is rich in cyclohexane. As the second milliliter is distilled, the temperature increases by ~ 20 &#176;C, which tells us that the amount of toluene in the vapor is increasing significantly. The temperature stabilizes as it approaches 111 &#176;C, which tells us that the vapor is rich in toluene towards the end of the distillation.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">Look at a boiling point diagram for cyclohexane and toluene, with the mole percent of cyclohexane and toluene on the x-axis and the temperature on the y-axis. The solid line denotes the bubble point, and the dashed line denotes the dew point.</div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">Use the dew point curve to determine the composition of the vapor throughout the distillation. For example, after 0.5 mL has been distilled, the condensing vapor is about 84 &#176;C. This corresponds to 95% cyclohexane on the dew point curve.</div>
		</li>
		<li data-sub-note-item="2-5">
		<div class="lab-step">Once you know the composition of the vapor at each point, estimate the composition of the boiling mixture throughout the distillation. At room temperature, cyclohexane and toluene have nearly the same number of moles per milliliter, so think of the percentages in terms of volume.</div>
		</li>
		<li data-sub-note-item="2-6">
		<div class="lab-step">To determine how much of each liquid was distilled in each step, apply each percentage to the volume of liquid distilled since the previous measurement. This tells us that we distilled 1.9 mL of cyclohexane and 1.1 mL of toluene from our mixture of 2 mL of each liquid. Thus, our distillate was 63% cyclohexane and 37% toluene, and our remaining liquid mixture was 10% cyclohexane and 90% toluene.</div>
		</li>
	</ul>
	</li>
</ol>

Simple Distillation: Separation of a Mixture of Cyclohexane and Toluene - Procedure

Prosta destylacja

Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA

	Simple DistillationExpand
	In this lab, you will use ...

Steam Distillation

<p>Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Steam Distillation<button class="expand">Expand</button>
	<p>In this experiment, you will perform a steam distillation to extract an essential oil from an orange peel.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-2">
		<div class="lab-step">Before you start the lab, put on the appropriate personal protective equipment, including a lab coat, safety goggles, and gloves. This experiment must be performed in a hood.</div>
		</li>
		<li data-sub-note-item="1-3">
		<div class="lab-step">First, you will need to assemble the steam distillation apparatus. Check the apparatus set up by your instructor.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Set the two stands next to each other in the hood. Place the stir plate on the base of one of the stands and set the heating mantle on top of it. Plug the heating mantle into the temperature controller, but do not turn it on yet.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Now, obtain a watch glass with 3 dried orange peels from your instructor. Weigh the orange peels on the balance and record the mass of the orange peels in your notebook.
		<h4><strong>Table 1: Mass of essential oil recovered</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always" height="166" width="476">
			<tbody>
				<tr>
					<td>Temperature of steam distillation (&#176;C)</td>
					<td></td>
				</tr>
				<tr>
					<td>Mass of the orange peels (g)</td>
					<td>&#160; &#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</td>
				</tr>
				<tr>
					<td>Mass of empty flask (g)</td>
					<td></td>
				</tr>
				<tr>
					<td>Mass of flask + essential oils (g)</td>
					<td></td>
				</tr>
				<tr>
					<td>Mass of essential oils (g)</td>
					<td></td>
				</tr>
				<tr>
					<td>Percent mass of essential oil recovered</td>
					<td></td>
				</tr>
			</tbody>
		</table>
		<a href="https://jove.unicartagenaproxy.elogim.com/CDNSource/lm/labs/61/Table_1._Mass_of_essential_oil_recovered.xlsx" target="_blank">Click Here to download Table 1</a></div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Bring your dried peels, funnel, spatula, and the 500-mL round-bottom flask to the instructor&#39;s bench and place the peels in the blender. Add about 4 mL of deionized water to the peels. Then, blend them until they are well mixed and smooth.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Using the funnel, transfer the blended peels to the round-bottom flask. Clamp the flask to the stand above the heating mantle.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Measure 200 mL of deionized water using your graduated cylinder and transfer it to the round-bottom flask using a funnel. Remove the funnel and add a stir bar to the flask.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Locate the Claisen adapter and apply a thin layer of grease to the joint. Then, insert the Claisen adapter into the flask.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Grease the thermometer adapter and insert it into the distilling head.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">Gently insert the thermometer into the distilling head by pushing and twisting through the adapter until the thermometer bulb is below the bend of the distilling head.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Lightly grease the lower joint of the distilling head, and then insert it into the outer arm of the Claisen adapter.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Now, obtain the condenser and carefully clamp it to the second stand. It should be oriented nearly horizontally, with the end closest to the distilling head slightly higher.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">Lightly grease the condenser and the side joint of the distilling head before connecting them.</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Next, attach one piece of rubber tubing to the inlet of the condenser, which is the port furthest away from the distilling head. Attach the other end to the tap water faucet in the hood.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">Connect the second piece of rubber tubing to the other port, which is the outlet, and place the end of the tubing in the drain.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Locate the separatory funnel and make sure that the stopcock is closed by turning it until it is fully horizontal.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">Insert the separatory funnel into the Claisen adapter, and add approximately 100 mL of deionized water to the funnel.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">Pick up the connecting joint and attach it to the end of the condenser.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">Then, attach a 250-mL round-bottom flask to the connecting joint using a plastic clip.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">Finally, check all of the joints to make sure they are tightly connected and then secure each one with a plastic clip.</div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">Now that the steam distillation apparatus is fully assembled, start the procedure. First, slowly turn the tap water on to fill the condenser with water. <strong>Note</strong>: Be sure to turn the water on slowly, or the tubing may pop off and cause a flood.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Next, turn on the magnetic stirrer at the lowest setting and set the temperature controller to the appropriate setting to reach about 90 &#176;C.</div>
		</li>
		<li data-sub-note-item="1-24">
		<div class="lab-step">Once bubbles start forming in the mixture and liquid is dripping into the collection flask, adjust the heat to increase or decrease the rate of distillation to about 20 drops/min.</div>
		</li>
		<li data-sub-note-item="1-25">
		<div class="lab-step">Record the temperature on the thermometer in your notebook. Now, carefully open the stopcock on the separatory funnel to slowly add water to the flask. Your goal is to add water at the same rate as distillation, about 20 drops/min.</div>
		</li>
		<li data-sub-note-item="1-26">
		<div class="lab-step">Allow the distillation to proceed and collect about 50 mL of distillate.<strong> Note:</strong> Be patient, since this should take about 2 hours. The liquid in the flask will become less cloudy as more oil is collected.</div>
		</li>
		<li data-sub-note-item="1-27">
		<div class="lab-step">Once you have collected enough distillate, turn off the heat. Then, shut off the water to the condenser and carefully raise the entire setup.</div>
		</li>
		<li data-sub-note-item="1-28">
		<div class="lab-step">Allow it to cool completely before removing the heating mantle and disassembling the glassware.</div>
		</li>
		<li data-sub-note-item="1-29">
		<div class="lab-step">Empty the separatory funnel of any remaining water and pour the orange pulp down the drain.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Extraction of Essential Oil<button class="expand">Expand</button>
	<p>Liquid-liquid extraction is performed in a separatory funnel and is used to move a solute to another liquid in which it is more soluble. The two liquids must be immiscible and are usually an aqueous solution and a non-water-soluble organic liquid. Upon mixing, the solute is extracted into the other phase. Once the liquids settle into layers, they can be drained from the funnel one at a time.</p>
	<p>In the next part of the experiment, liquid-liquid extraction will be used to extract the essential oil from the water into an organic solvent. You&#39;ll then evaporate the organic solvent to recover the essential oil.</p>
	<ul class="lab-items">
		<li data-sub-note-item="2-3">
		<div class="lab-step">Before starting the experiment, first, make sure that the separatory funnel is rinsed and clean.</div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">Label the two 250-mL beakers as &#8216;organic layer&#8217; and &#8216;aqueous layer&#8217;. Then, attach a ring support to one of the stands.</div>
		</li>
		<li data-sub-note-item="2-5">
		<div class="lab-step">Place the separatory funnel in the support. Make sure that the stopcock is closed and the separatory funnel is secure. Then, transfer the distillate into the separatory funnel.</div>
		</li>
		<li data-sub-note-item="2-6">
		<div class="lab-step">Measure 20 mL of diethyl ether at the instructor&#39;s hood and bring it back to your workstation. Pour the diethyl ether into the separatory funnel with the distillate. <strong>Note:</strong> You should see the immiscible liquids form two layers in the funnel. The top layer is the diethyl ether.</div>
		</li>
		<li data-sub-note-item="2-7">
		<div class="lab-step">Apply a thin layer of vacuum grease to the separatory funnel stopper and insert it into the top of the funnel.</div>
		</li>
		<li data-sub-note-item="2-8">
		<div class="lab-step">Hold the stopper in place and shake the separatory funnel vigorously for about 1 min.</div>
		</li>
		<li data-sub-note-item="2-9">
		<div class="lab-step">Occasionally, vent the funnel by turning it upside down and opening, then closing the stopcock. Be sure to do this inside of the hood and away from your face.</div>
		</li>
		<li data-sub-note-item="2-10">
		<div class="lab-step">Once you have finished mixing the contents, vent the funnel again, close the stopcock, and then place the funnel in the ring attached to the stand.</div>
		</li>
		<li data-sub-note-item="2-11">
		<div class="lab-step">Allow the aqueous and organic layers to fully separate. Then, place the aqueous layer beaker under the separatory funnel.</div>
		</li>
		<li data-sub-note-item="2-12">
		<div class="lab-step">Remove the stopper and slowly open the stopcock to drain the aqueous layer into the beaker. Carefully watch the solution drain and be sure to close the stopcock before the next layer is drained.</div>
		</li>
		<li data-sub-note-item="2-13">
		<div class="lab-step">Replace the aqueous layer beaker with the organic layer beaker. Open the stopcock and drain the organic layer into its beaker.</div>
		</li>
		<li data-sub-note-item="2-14">
		<div class="lab-step">Now, close the stopcock and return the contents of the aqueous layer beaker to the separatory funnel, add 20 mL of diethyl ether, and repeat the extraction.</div>
		</li>
		<li data-sub-note-item="2-15">
		<div class="lab-step">Open the stopcock and drain the aqueous layer into the appropriate beaker, and then drain the organic layer into the organic layer beaker, adding it to the organic layer from the first extraction.</div>
		</li>
		<li data-sub-note-item="2-16">
		<div class="lab-step">Now, obtain magnesium sulfate in a weighing boat and scoop a small spatula of it into the organic layer beaker. Swirl the beaker, and then let it sit for about 20 min.</div>
		</li>
		<li data-sub-note-item="2-17">
		<div class="lab-step">After 20 min, remove the separatory funnel and ring and mount a regular clamp to the lab stand.</div>
		</li>
		<li data-sub-note-item="2-18">
		<div class="lab-step">Weigh an empty 125-mL Erlenmeyer flask and record the mass in your notebook. Then, clamp the flask to the stand and place a conical glass funnel in its neck.</div>
		</li>
		<li data-sub-note-item="2-19">
		<div class="lab-step">Fold your filter paper in half and in half again. Then, open the filter paper on one side to create a cone. Place the cone inside the conical funnel.</div>
		</li>
		<li data-sub-note-item="2-20">
		<div class="lab-step">Now, filter the magnesium sulfate from the organic layer.</div>
		</li>
		<li data-sub-note-item="2-21">
		<div class="lab-step">Next, set your hot plate to 40 &#176;C and place a large beaker containing 400 mL of water on it. Place the Erlenmeyer flask in the warm water bath and allow the organic solvent to evaporate in the hood.</div>
		</li>
		<li data-sub-note-item="2-22">
		<div class="lab-step">Once the organic solvent has fully evaporated, remove the Erlenmeyer flask from the water bath and dry the outside with paper towels.</div>
		</li>
		<li data-sub-note-item="2-23">
		<div class="lab-step">Weigh the cooled flask and record the mass in your notebook.</div>
		</li>
		<li data-sub-note-item="2-24">
		<div class="lab-step">Now that the experiment is complete, be sure to properly clean up your workspace by disposing of all solutions in the non-halogenated waste.</div>
		</li>
		<li data-sub-note-item="2-25">
		<div class="lab-step">Wash all of the glassware using detergent and then rinse them with acetone and deionized water.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="3" data-parent-collapse="">Results<button class="expand">Expand</button>
	<ul class="lab-items">
		<li data-sub-note-item="3-1">
		<div class="lab-step">Determine the mass of the oil extracted from the orange peel by subtracting the mass of the empty flask from the mass of the flask with oil.</div>
		</li>
		<li data-sub-note-item="3-2">
		<div class="lab-step">Calculate the percentage of oil in the orange peel using the original mass of the dried peel. Typically, the steam distillation method recovers about 0.9 &#8211; 4 wt% of an orange peel&#8217;s mass as essential oil.</div>
		</li>
	</ul>
	<p>You distilled the essential oil in this lab at close to 100 &#176;C. The orange oil consists mainly of (+)limonene, which has a boiling point of 176 &#176;C. Thus, the steam distillation technique lets us extract it from the orange peel at a temperature that will not compromise its structure.</p>
	</li>
</ol>

Steam Distillation: Extraction of Essential Oil from Orange Peel - Procedure

Destylacja z parą wodną

Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA

	Steam DistillationExpand
	In this experiment, you will ...

Synthesis of Luminol

<p>Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Synthesis of 3-Nitrophthalhydrazide<button class="expand">Expand</button>
	<p>In this lab, you&#39;ll synthesize 3-aminophthalhydrazide, which is also called luminol, in a 2-step process. The first step is a condensation reaction between 3-nitrophthalic acid and hydrazine.</p>
	<p>During this step, the carboxylic acid groups are substituted with NH groups to produce 3-nitrophthalhydrazide and two water molecules. You must work in a fume hood throughout this lab because the reactions produce toxic vapors and gases.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-3">
		<div class="lab-step">Before you get started, put on a lab coat, splash-proof safety glasses, and nitrile gloves. <strong>Note:</strong> Hydrazine is highly toxic and flammable, so avoid touching it and keep anything containing hydrazine closed or covered when you transport it between fume hoods.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Now measure 10 mL of deionized water and pour it into a 25-mL Erlenmeyer flask. Clamp the flask on a hot plate and place a thermometer in it.</div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Then, start heating the water. You&#39;ll want the temperature of the water to be 80 &#176;C, so set the hot plate setting to slightly higher.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">While it heats, set up a Bunsen burner under a clamp fixed on a lab stand.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Obtain a 25-mL test tube and adjust the clamp so that it will hold the test tube about 5 &#8211; 7 cm above the flame. Then, remove the test tube and place it in a 400-mL beaker.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Once the water reaches 80 &#176;C, adjust the heat setting to keep the temperature stable.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Then, weigh 0.6 g of 3-nitrophthalic acid in a tared weighing boat. Pour the 3-nitrophthalic acid into your test tube. Then, bring the test tube and a test tube stopper to the solvent hood.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Use the provided volumetric pipette to carefully measure 0.9 mL of the 10% v/v hydrazine solution and transfer it to the test tube. Remember to cap the bottle of hydrazine solution and stopper your test tube before you return to your hood.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">Clamp the test tube over the Bunsen burner and remove the stopper. Then, pour ~2 mL of triethylene glycol into a graduated cylinder and set it out of the way in your hood.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Now, add 2 or 3 boiling chips to the test tube. Place a high-temperature thermometer in the test tube and ignite the Bunsen burner. Heat the mixture with a medium flame until the 3-nitrophthalic acid dissolves.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Then, add the triethylene glycol and increase the heat of the flame. <strong>Note:</strong> Once the water from the hydrazine solution has boiled off, the temperature will continue increasing.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">When the reaction mixture reaches 210 &#176;C, turn down the heat and keep the mixture between 210 &#176;C and 220 &#176;C for 3 &#8211; 4 min.</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Then, extinguish the flame and wait for the mixture to cool to 100 &#176;C.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">Turn off the hotplate, remove the thermometer, and unclamp the flask. Use tongs to hold the flask and measure 8 mL of hot water with the graduated cylinder. Pour this hot water into the test tube and remove the thermometer.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Obtain a piece of plastic paraffin film and cover the mouth of the test tube. Then, use tongs to transfer the test tube to the holding beaker.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">At a lab sink, hold the test tube under running tap water to cool it, being careful not to let water into it.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">Then, dry the outside of the tube and bring it back to your hood. Clamp the tube upright and remove the paraffin film. Let the yellow 3-nitrophthalhydrazide precipitate in the tube for 15 min.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">While you wait, add ~10 mL of deionized water to a 25-mL Erlenmeyer flask. Prepare an ice bath in a 250-mL beaker and start chilling the water in it.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">Then, set up for vacuum filtration using a 250-mL filter flask, a B&#252;chner funnel, and a piece of circular filter paper.</div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">Once the product has precipitated for at least 15 min, obtain a Pasteur pipette and wet the filter paper with a few drops of cold water.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Then, turn on the vacuum and pour the contents of the test tube into the B&#252;chner funnel. Rinse the remaining solid into the funnel with 1 &#8211; 2 mL of cold water.</div>
		</li>
		<li data-sub-note-item="1-24">
		<div class="lab-step">Remove the boiling chips with tweezers and rinse them with a few drops of cold water to finish collecting the product.</div>
		</li>
		<li data-sub-note-item="1-25">
		<div class="lab-step">Turn off the vacuum pump once no more liquid is dripping into the flask from the funnel.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Synthesis of 3-Aminopthalhydrazide<button class="expand">Expand</button>
	<p>In the second step of the luminol synthesis, you&#39;ll reduce the nitro group of 3-nitrophthalhydrazide using sodium dithionite in a basic solution of NaOH. This will produce 3-aminophthalhydrazide dianion.</p>
	<p>After the reduction, you&#39;ll add acetic acid to protonate the dianion, forming luminol. Sodium dithionite is highly reactive and degrades quickly, so you&#39;ll use a slight excess of it. After the reduction, you&#39;ll protonate the luminol dianion to decrease its solubility in water. Lastly, you&#39;ll precipitate and collect luminol as a yellow solid.</p>
	<ul class="lab-items">
		<li data-sub-note-item="2-3">
		<div class="lab-step">Place a clean 25-mL test tube in a beaker and use a clean spatula to transfer your 3-nitrophthalhydrazide to the test tube.</div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">Set the B&#252;chner funnel aside and clamp the test tube over the Bunsen burner. Leave the filter flask in place for later.</div>
		</li>
		<li data-sub-note-item="2-5">
		<div class="lab-step">Now, use a 10-mL graduated cylinder to obtain 3 mL of approximately 3 M NaOH. Pour the sodium hydroxide solution into the test tube and stir the mixture with a glass rod until the 3-nitrophthalhydrazide dissolves.</div>
		</li>
		<li data-sub-note-item="2-6">
		<div class="lab-step">Now, weigh 2 g of sodium dithionite in a tared weighing boat and add it to the test tube. Obtain 3 mL of deionized water and pour it into the tube.</div>
		</li>
		<li data-sub-note-item="2-7">
		<div class="lab-step">Stir the mixture well to dissolve as much of the solid as you can. Then, add a few clean boiling chips to the test tube and ignite the Bunsen burner.</div>
		</li>
		<li data-sub-note-item="2-8">
		<div class="lab-step">Heat the mixture to boiling over a medium flame and then let it boil for 5 min.</div>
		</li>
		<li data-sub-note-item="2-9">
		<div class="lab-step">While you wait, measure 1.5 mL of glacial acetic acid and bring it to your hood.</div>
		</li>
		<li data-sub-note-item="2-10">
		<div class="lab-step">Once the reaction mixture has boiled for 5 min, shut off the Bunsen burner and add the acetic acid to the tube. Let the mixture cool to room temperature, which usually takes 10 &#8211;15 minutes. Meanwhile, prepare an ice bath in a 600-mL beaker.</div>
		</li>
		<li data-sub-note-item="2-11">
		<div class="lab-step">Once the mixture has cooled, place it in the ice bath and wait 15 min for the luminol to precipitate.</div>
		</li>
		<li data-sub-note-item="2-12">
		<div class="lab-step">Reassemble the vacuum filtration setup using a clean B&#252;chner funnel and a new piece of filter paper, and start cooling another 10 mL of deionized water in an ice bath.</div>
		</li>
		<li data-sub-note-item="2-13">
		<div class="lab-step">Once the luminol has been in the ice bath for at least 15 min, wet the filter paper with cold water. Then, collect the solid luminol by vacuum filtration.</div>
		</li>
		<li data-sub-note-item="2-14">
		<div class="lab-step">Retrieve the boiling chips and rinse the luminol with more cold water. Once liquid stops dripping from the funnel, turn off the vacuum and transfer the luminol to a 50-mL beaker.</div>
		</li>
		<li data-sub-note-item="2-15">
		<div class="lab-step">Now, prepare the combined filtrate for disposal. First, label a 250-mL beaker &#8216;hydrazine and dithionite waste&#8217;. Transfer the filtrate to the beaker and rinse the flask with deionized water to remove residual hydrazine and dithionite.</div>
		</li>
		<li data-sub-note-item="2-16">
		<div class="lab-step">Next, dilute the filtrate with 10 mL of deionized water. Then, measure 10 mL of 1 M sodium carbonate and add it to the combined filtrates.</div>
		</li>
		<li data-sub-note-item="2-17">
		<div class="lab-step">Bring a 50-mL graduated cylinder to the waste hood. Measure 40 mL of 10% sodium hypochlorite and pour it into the filtrate mixture. Place the beaker on the hot plate, add a stir bar, and secure a thermometer in the beaker.</div>
		</li>
		<li data-sub-note-item="2-18">
		<div class="lab-step">Heat the mixture to 50 &#176;C while stirring. The mixture must stay at 50 &#176;C for 1 h to oxidize leftover hydrazine and dithionite, so make sure that the temperature is stable and set a timer for 1 h before starting the last part of the lab.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="3" data-parent-collapse="">Chemiluminescence and&#160;Fluorescence<button class="expand">Expand</button>
	<p>For the last part of the lab, you&#39;ll mix some of the luminol you made with dimethyl sulfoxide over solid potassium hydroxide. The hydroxyl ions deprotonate the two amine groups. Then, ambient oxygen oxidizes the luminol dianion to 3-aminophthalate, or 3-APA, in an excited state. This unstable complex will quickly relax to the ground state, releasing energy as visible light. Since the excited 3-APA was the product of a chemical reaction, the emitted light is called chemiluminescence.</p>
	<p>Once you have seen the chemiluminescence from the oxidation reaction, you&#39;ll add fluorescein, a fluorescent molecule, to the mixture. Some excited 3-APA will transfer energy directly to fluorescein rather than emitting light, giving you a solution with two different light-emitting compounds.</p>
	<ul class="lab-items">
		<li data-sub-note-item="3-3">
		<div class="lab-step">Now, measure about 0.2 g of the luminol you made and place it in a 15-mL Erlenmeyer flask. It&#39;s OK if the solid is still damp.</div>
		</li>
		<li data-sub-note-item="3-4">
		<div class="lab-step">Obtain 5 &#8211; 7 pellets of potassium hydroxide and pour them into the flask. Then, bring the flask, a stopper, and a 10-mL graduated cylinder to the solvent hood.</div>
		</li>
		<li data-sub-note-item="3-5">
		<div class="lab-step">Measure 2 mL of DMSO, add it to the flask, and stopper it. Put the graduated cylinder in your fume hood and bring the flask to a dark room.</div>
		</li>
		<li data-sub-note-item="3-6">
		<div class="lab-step">Shake the stoppered flask vigorously until you see chemiluminescence and then put the flask down. The light fades quickly because both the oxidation and relaxation are fast processes.</div>
		</li>
		<li data-sub-note-item="3-7">
		<div class="lab-step">Shake the flask and let the light fade 6 &#8211; 10 more times without opening the flask. The light will be progressively dimmer as the oxygen in the flask is consumed. <strong>Note:</strong> To make it brighter, leave the flask open in your fume hood for a minute to replenish the oxygen.</div>
		</li>
		<li data-sub-note-item="3-8">
		<div class="lab-step">Close the flask, return to the dark room, and shake the flask again to see the effect.</div>
		</li>
		<li data-sub-note-item="3-9">
		<div class="lab-step">Now, measure 0.2 g of fluorescein dye and add it to your flask. Stopper the flask and return to the dark room. Shake the flask vigorously until the mixture is glowing brightly and then set it down to observe the difference in color from luminol alone.</div>
		</li>
		<li data-sub-note-item="3-10">
		<div class="lab-step">When you&#39;re finished, check on the filtrate. Once it has been at 50 &#176;C for at least 1 h, turn off the hotplate and wait for the beaker to cool to room temperature.</div>
		</li>
		<li data-sub-note-item="3-11">
		<div class="lab-step">Then, add about 10 mL of tap water to the filtrate and flush it down the drain.</div>
		</li>
		<li data-sub-note-item="3-12">
		<div class="lab-step">Dispose of the remaining chemical and glass waste in the appropriate containers, clean your glassware and tools, and put away your lab equipment.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="4" data-parent-collapse="">Results<button class="expand">Expand</button>
	<p>Under your oxidation reaction conditions, excited 3-APA emits blue-green light in a broad range around 500 nm when it relaxes, and fluorescein is excited by absorbing light at 480 &#8211; 490 nm and 515 &#8211; 525 nm.</p>
	<p>When you add fluorescein to the luminol oxidation reaction mixture, excited 3-APA can transfer energy that fluorescein would absorb as light directly to a nearby fluorescein molecule in a special interaction called nonradiative energy transfer. The resulting excited fluorescein emits yellow-green light when it relaxes.</p>
	<p>Excited 3-APA is highly unstable, so if no fluorescein is close enough for nonradiative energy transfer, it will relax by emitting light as usual. Thus, a spectrum of your final glowing mixture would show contributions from both blue-green and yellow-green light.</p>
	<ul class="lab-items">
	</ul>
	</li>
</ol>

Synthesis of Luminol and Chemiluminescence - Procedure

Synteza luminolu

Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA

	Synthesis of 3-NitrophthalhydrazideExpand
	In this lab, ...

Esterification

<p>Source: Lara Al Hariri at the University of Massachusetts Amherst, MA, USA</p>
<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Esterification<button class="expand">Expand</button>
	<p>In this lab, you will synthesize an ester from a carboxylic acid and an alcohol in the presence of sulfuric acid. This reaction is called Fischer esterification. The sulfuric acid makes the carboxylic acid more reactive towards the alcohol. Without it, esterification would be slow and unfavorable. Esterification is highly reversible, so you&#39;ll use an excess of alcohol to drive the reaction towards the ester.</p>
	<p>You will be assigned one of seven carboxylic acid-alcohol pairs for your reaction. Each of the seven possible product testers has a distinct fruity scent. When you finish the reaction, you will waft your products vapor towards yourself and identify it based on the fruit that it smells like.</p>
	<ul class="lab-items">
		<li data-sub-note-item="1-3">
		<div class="lab-step">Before you get started, put on a lab coat, safety glasses, and nitrile gloves. <strong>Note: </strong>Your instructor will demonstrate wafting before handing out the reagents. Always smell compounds by wafting, rather than direct inhalation.</div>
		</li>
		<li data-sub-note-item="1-4">
		<div class="lab-step">Once you are ready to begin, get your assigned carboxylic acid and alcohol and bring the vials to your fume hood. The vial labeled &#8216;A&#8217;, &#8216;B&#8217;, or &#8216;C&#8217; is your carboxylic acid. The other vial is the alcohol. Record the letters of your carboxylic acid and alcohol in your lab notebook.
		<h4><strong>Table 1: Scent of Carboxylic Acid, Alcohol, and Ester</strong></h4>
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td></td>
					<td><strong>Letter </strong></td>
					<td><strong>Scent </strong></td>
				</tr>
				<tr>
					<td>Assigned carboxylic acid</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Assigned alcohol</td>
					<td></td>
					<td></td>
				</tr>
				<tr>
					<td>Synthesized ester</td>
					<td></td>
					<td></td>
				</tr>
			</tbody>
		</table>
		<a href="https://jove.unicartagenaproxy.elogim.com/CDNSource/lm/labs/68/Table_1._Scent_of_carboxylic_acid,_alcohol,_and_ester.xlsx" target="_blank">Click Here to download Table 1</a></div>
		</li>
		<li data-sub-note-item="1-5">
		<div class="lab-step">Now, get a piece of filter paper and a Pasteur pipette. In the fume hood, use the Pasteur pipette to apply a drop of your alcohol to the filter paper.</div>
		</li>
		<li data-sub-note-item="1-6">
		<div class="lab-step">Bring the filter paper to the front of the hood and waft the scent of the alcohol towards yourself. Be careful because it might smell unpleasant.</div>
		</li>
		<li data-sub-note-item="1-7">
		<div class="lab-step">Then, put the filter paper back in the hood and write a brief description of the scent of the alcohol in your lab notebook. Do the same for your carboxylic acid if it&#39;s a liquid using a new pipette and piece of filter paper. <strong>Note:</strong> If you were assigned a solid carboxylic acid, write &#39;solid&#39; in your lab notebook and skip this step.</div>
		</li>
		<li data-sub-note-item="1-8">
		<div class="lab-step">Now, attach an open 3-prong clamp to a lab stand in your fume hood. Place a lab jack at the base of the stand and set a stir plate and a heating mantle on top of it. Move the temperature controller next to the setup.</div>
		</li>
		<li data-sub-note-item="1-9">
		<div class="lab-step">Then, place a small stir bar in a 50-mL round-bottom flask and securely clamp the flask over the heating mantle.</div>
		</li>
		<li data-sub-note-item="1-10">
		<div class="lab-step">Add the carboxylic acid to the flask using a funnel. Rinse the carboxylic acid vial into the flask with 1 or 2 mL of your alcohol, and then add the rest of the alcohol to the flask.</div>
		</li>
		<li data-sub-note-item="1-11">
		<div class="lab-step">Next, bring a 10-mL graduated cylinder to the fume hood reserved for acids, and carefully measure 4 mL of 3 M sulfuric acid. <strong>Note:</strong> It&#39;s highly toxic and corrosive, so be careful with it.</div>
		</li>
		<li data-sub-note-item="1-12">
		<div class="lab-step">Cover your graduated cylinder with plastic paraffin film. Then, bring the acid back to your hood and add it to the flask. It&#39;s OK if the liquids form two layers.</div>
		</li>
		<li data-sub-note-item="1-13">
		<div class="lab-step">Now, use one piece of tubing to connect the lower arm of the standard condenser to the water tap in your fume hood. Attach the other piece of tubing to the upper arm and direct it to your drain. Make sure that the connections are secure.</div>
		</li>
		<li data-sub-note-item="1-14">
		<div class="lab-step">Apply vacuum grease to the lower ground glass joint of the condenser. Fit the condenser into the round-bottom flask and ensure that the grease forms a good seal.</div>
		</li>
		<li data-sub-note-item="1-15">
		<div class="lab-step">Secure the condenser in place with a second 3-prong clamp and make sure that the tubing is out of the way. Use a laboratory wipe to remove excess grease, and then secure the connection with a joint clip.</div>
		</li>
		<li data-sub-note-item="1-16">
		<div class="lab-step">Now, slowly open the water tap until water is flowing smoothly through the condenser. Make sure that the water is flowing into the drain and that there are no leaks.</div>
		</li>
		<li data-sub-note-item="1-17">
		<div class="lab-step">Then, raise the lab jack until the round-bottom flask is sitting in the heating mantle. You are now ready to start heating your reaction mixture to reflux.</div>
		</li>
		<li data-sub-note-item="1-18">
		<div class="lab-step">Set the stir motor to medium speed and start heating the mixture on medium heat or with a set point of about 110 &#176;C.</div>
		</li>
		<li data-sub-note-item="1-19">
		<div class="lab-step">The first boiling point of your mixture will be between 65 and 100 &#176;C. So, keep an eye on it as it heats and adjust the temperature setting as needed.</div>
		</li>
		<li data-sub-note-item="1-20">
		<div class="lab-step">Once the mixture reaches an even boil, let it reflux for 50 min.</div>
		</li>
		<li data-sub-note-item="1-21">
		<div class="lab-step">Then, turn off the heat, lower the lab jack, and replace the heating mantle with a round bottom flask holder.</div>
		</li>
		<li data-sub-note-item="1-22">
		<div class="lab-step">Let the mixture cool to room temperature with the condenser still in place, which usually takes about 10 min. During that time, prepare an ice bath in a 600-mL beaker and bring it to your fume hood.</div>
		</li>
		<li data-sub-note-item="1-23">
		<div class="lab-step">Once the mixture has cooled completely, turn off the flow of water to the condenser. Carefully separate the condenser from the flask and move it out of the way. Then, raise the ice bath up to the flask and let it cool for 10 min.</div>
		</li>
		<li data-sub-note-item="1-24">
		<div class="lab-step">After that, bring a clean 10-mL graduated cylinder to the base hood and obtain 5 mL of saturated sodium bicarbonate.</div>
		</li>
		<li data-sub-note-item="1-25">
		<div class="lab-step">Back at your hood, use a lab wipe to remove vacuum grease from the inside of the neck of the round bottom flask.</div>
		</li>
		<li data-sub-note-item="1-26">
		<div class="lab-step">Then, obtain several clean Pasteur pipettes and some pH paper. Use a pipette to slowly add 1 mL of saturated sodium bicarbonate to the flask and stir the mixture with a stir bar or a glass rod.</div>
		</li>
		<li data-sub-note-item="1-27">
		<div class="lab-step">Add the rest of the sodium bicarbonate solution a milliliter at a time, stirring after each addition.</div>
		</li>
		<li data-sub-note-item="1-28">
		<div class="lab-step">Then, use a new pipette to check the pH of the solution. If the pH is &#60; 7, get a few more milliliters of sodium bicarbonate and add it 1 mL at a time, stirring and checking the pH after each addition.</div>
		</li>
		<li data-sub-note-item="1-29">
		<div class="lab-step">Once the solution is at a neutral pH, remove the ice bath and dry the outside of the flask with a paper towel.</div>
		</li>
		<li data-sub-note-item="1-30">
		<div class="lab-step">Let the mixture sit for a few minutes to see whether it settles into two layers.</div>
		</li>
		<li data-sub-note-item="1-31">
		<div class="lab-step">Then, obtain a clean Pasteur pipette and a new piece of filter paper. Carefully draw up a small amount of the product solution and apply one or two drops to the filter paper. If your product mixture separated, test the top layer first.</div>
		</li>
		<li data-sub-note-item="1-32">
		<div class="lab-step">Bring the filter paper to the edge of the fume hood and waft the set towards yourself. The seven possible scents are apple, banana, grape, orange, pear, pineapple, and strawberry.</div>
		</li>
		<li data-sub-note-item="1-33">
		<div class="lab-step">Record the fruit that you think your ester smells like in your lab notebook. If you aren&#39;t sure which fruit it is, ask your instructor for the reference scents to help you decide.</div>
		</li>
		<li data-sub-note-item="1-34">
		<div class="lab-step">Once you&#39;ve identified the smell of your ester, retrieve the stir bar, and dispose of your reaction mixture in the non-halogenated organic waste container. Clean your glassware and stir bar using your usual methods.</div>
		</li>
		<li data-sub-note-item="1-35">
		<div class="lab-step">Next, unclamp the condenser and carefully tilt it to let the water drain through the outlet tubing. Disconnect the inlet tubing from the water tap, keeping the end raised to avoid spills, and let the remaining water flow through the condenser to the drain.</div>
		</li>
		<li data-sub-note-item="1-36">
		<div class="lab-step">Then, disconnect the condenser from the tubing and remove the vacuum grease on the bottom joint with lab wipes. Clean the inner walls of the condenser using your usual methods.</div>
		</li>
		<li data-sub-note-item="1-37">
		<div class="lab-step">Leave the filter papers in the hood until they stop smelling strongly of fruit. Dispose of used Pasteur pipettes in the glass waste and throw out any other trash in the lab trash container.</div>
		</li>
		<li data-sub-note-item="1-38">
		<div class="lab-step">Lastly, put away your equipment and clean your hood before you leave.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Results<button class="expand">Expand</button>
	<p>Here are the seven possible esters that you could have made and their scents: propyl acetate smells like pear, isoamyl acetate smells like banana, octyl acetate smells like orange, butyl butyrate smells like pineapple, ethyl butyrate smells like strawberry, methyl butyrate smells like apple, and methyl anthranilate smells like grape.</p>
	<ul class="lab-items">
		<li data-sub-note-item="2-2">
		<div class="lab-step">Compare the scent of your ester to find the corresponding structure. For example, a strong scent of pears means that you made propyl acetate.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">Determine your starting carboxylic acid and alcohol. <strong>Note: </strong>Remember that alcohol attacks the carboxylic acid in this reaction. The resulting intermediate rearranges and eliminates a water molecule to form an ester.</div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">Studies have shown that the alkoxy oxygen comes from the alcohol, not the carboxylic acid. So, we&#39;ll split the ester diagram at the carbon-oxygen single bond and fill in the missing OH and H to get the starting materials. For example, if we split propyl acetate at that bond, add an OH to the carbonyl carbon and add a hydrogen to the alkoxy oxygen, we get acetic acid and 1-propanol as the starting materials.</div>
		</li>
	</ul>
	</li>
</ol>

Esterification: Synthesis of Ester by Fischer Esterification - Procedure

Estryfikacji

Source: Lara Al Hariri at the University of Massachusetts Amherst, MA, USA

	EsterificationExpand
	In this lab, you will synthesize an ester from a ...