Please answer the following question about a lab experiment about synthesizing aspirin. The procedure for this experiment is included in the photos.After dissolving the aspirin in hot ethanol, why does it crystallize when water is added to the solution? microscopic, angular fragment of glass) on which crystals can begin to grow.o Alternatively, you can obtain a small "seed" crystal of aspirin (just big enough to see) from anotherstudent or TA and add it to your mixture. Stir the solution with a stirring rod and wait for 1-2minutes to see any precipitation.o If none of these techniques work, repeat the synthesis.Step 2: Filtering the reaction product.• Set up the vacuum filtration apparatus as shownin Figure 1. Clamp the filter flask to the supportbars. Connect the filter flask to the trap flaskand not directly to the vacuum line. Use thethick vacuum tubing. Place a Buchnerfunnel with filter paper on the flask.Rubber bung/cork• Using a stirring rod, break up any large Rubber tubingparticles of solid in theprecipitate.moisten the filter• Turn on the vacuum line knob,paper with deionized water, and then filter the reaction mixture by slowly pouring the mixture intothe Buchner funnel. The filter flask will be getting full, so empty Figure 1: Filtration setup to be used forit into a large beaker and set it in the corner of your hood, thencontinue with the filtration.isolating aspirin from the reaction mixture.Buchner funnelcontaining moistenedfilter paperFiltrate containing impurities, acetic acid,water. Should be emptied periodically.Vacuum line•Now that much of the solid has been transferred to the filtration apparatus, use deionized waterand a glass stirring rod or spatula to transfer the remaining solid.•Rinse the beaker with 10-15 mL of deionized water, and then transfer the water and the remainingsolid to the funnel. Keep the vacuum on to remove the water. Dry the solid as much as possible bydrawing air through the filter for about 1-2 min. Then, turn off the vacuum.•Transfer the solid with or without the filter paper to a dry watch glass, being careful not to tear thefilter paper. The filtrate from the flask and the beaker can be disposed of in the waste container.Let the sample air dry for few minutes before transferring it to a 50 mL Erlenmeyer flask forrecrystallization in the next step. Weigh the crude aspirin.•Step 3: Recrystallization• Set aside a small amount (spatula tip full) of the crude aspirin you obtained to test it in a futurelab. Keep it in a small labeled test tube in your drawer.•Transfer the rest of the crude aspirin to a 50-mL Erlenmeyer flask. Take about 1-2 mL ethanol andheat the flask on the heating mantle. Add ethanol dropwise until all the solid dissolves.Remove the flask from the heat and slowly add water dropwise while stirring until a solid appears.Now heat the flask again to dissolve the solid and get a clear solution. You can add a few moredrops of ethanol if you are not getting a clear solution upon boiling.• Once it is clear let it cool to room temperature.•Crystals should form. Chill this flask in an ice-water bath, and collect the crystals using vacuumfiltration. (If crystals don't appear at room temperature, you may have to boil again to get rid ofsome solvent.)• Carefully lift the filter paper with the crystals on it and place it on a clean watch glass. Weigh therecrystallized aspirin. Leave this aspirin in your drawer to dry until the next laboratory period. ProcedureStep 1: Synthesis.A hot water bath needed for the reaction can be prepared in the fume hood. A water bath can be a100 mL beaker filled with 70 mL water. Use the heating mantle and transformer to heat the beaker.• Weigh about 2 g of salicylic acid. Record the mass to the nearest milligram. Transfer the solid to alarge test tube. Set the test tube in your test tube rack or a large beaker so it doesn't spill.Carefully add about 4 mL of acetic anhydride to the test tube containing salicylic acid using a10 mL graduated cylinder. Gently mix the contents, avoiding any spilling of the liquid. Most of thesolid will not dissolve at room temperature.• Carefully add about 5 drops of concentrated sulfuric acid to the mixture. Gently swirl to mix thesulfuric acid.••CAUTIONCAUTION: Acetic anhydride and conc. sulfuric acid are reactive and corrosive.Work with these compounds in the fume hood.Clamp the test tube to the support bars. Use the lab jack to raise the hot water bath to your test tube.Continue heating the water. After about 1 minute, swirl the contents of the large test tube using a testtube holder (wooden clothespin type) to dissolve any salicylic acid that was not dissolved initially.Leave the test tube in the hot water bath for 20 min. Do not start time until water is boiling.While the sample is being heated, fill one-fourth of a 250 mL beaker with ice (no more).After the reaction is complete, remove the test tube from hot water bath carefully using the test tubeholder. Turn off the heat. Add the contents of the test tube slowly into a water/ice mixture taken in the250 mL beaker while stirring continuously. Swirl the mixture to decompose all the acetic anhydride.Rinse the test tube with deionized water several times using a wash bottle, adding the rinse water tothe water/ice beaker after swirling the water to transfer all the material to the beaker.•Let the sample cool to room temperature. A white precipitate will form. BE PATIENT!If the product doesn't precipitate, try the following:oWait for 2-3 minutes and then "scratch" the mixture. That is, use your glass stirring rod and gentlyrub it along the side of the beaker. If done properly, that will provide a nucleation site (a2

We have to explain the cause of recrystallization of aspirin in presence of water.

Answered: After dissolving the aspirin in hot…

1st Edition

ISBN:9780078746376

Author:Dinah Zike, Laurel Dingrando, Nicholas Hainen, Cheryl Wistrom

Publisher:Dinah Zike, Laurel Dingrando, Nicholas Hainen, Cheryl Wistrom

Chapter13: Gases

Section: Chapter Questions

Problem 117A