Indexpagechem234 Chemistry 234 - University of Illinois ... Archives... · Experiment Schedule Chemistry 234 - Fall, 2001 ... August 27-31 1 Check In, ... Chem 234 provides you with

Chemistry 234Organic Chemistry Laboratory

Title page

Schedule ofExperiments

General Information

Check-in

Laboratory Safety

Lab 1 -- MeltingPoint

Lab 2 --Recrystallization

Lab 3 -- FractionalDistillation

Lab 4 -- Extraction

Lab 5 --2-chloro-2-methylpropane

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Lab 6 --Methylbenzoate

Lab 7 -- Methylm-nitrobenzoate

Lab 8 --Cyclohexene

Lab 9 --Anisalacetophenone

Lab 10 --Identification ofUnknowns

Check-out

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Experiment ScheduleChemistry 234 - Fall, 2001

Text: Experimental Organic Chemistry* [EOC] by J. C. Gilber and S. F. Martin. Publisher:Saunders, 2001, 3rd Edition

Part I - Introduction to Laboratory Techniques (55 points)Date range Lab Periods Experiment Reading* [EOC] CreditAugust 27-31 1 Check In, Melting Points 37-39, 107-111 10Sept. 4-10 1 Recrystallization 88-107 10Sept. 11-17 1 Fractional Distillation 116-140 15Sept. 18-24 1 Extraction 70-73, 141-158 20

Part II - Synthesis (110 points)Date range Lab Periods Experiment Reading* [EOC] CreditSept. 25-Oct.1 1 2-chloro-2-methylpropane 423-427, 435-439 20Oct. 2-15 2 methyl benzoate Syllabus 40Oct. 16-22 1 methyl m-nitrobenzoate Syllabus 25Oct.23-29 1 cyclohexene Syllabus 20Oct. 30-Nov. 5 1 anisalacetophenone 569-573 25

Part III - Identification of Organic Compounds (65 points)Date range Lab Periods Experiment Reading* [EOC] Credit

Nov. 6-26 2 Identification of an aldehyde,amine, alcohol or ketone

735-738, 746-748,751-767, 777-781,788-794

45

Nov. 27-Dec. 3 Make-up and checkout*Note: All pages indicated in this column refer to the text book, Experimental OrganicChemistry, 3rd Edition. Before coming to lab, you are expected to read these pages indicatedabove as well as the corresponding pages in this Lab Manual.

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General InformationCourse Objectives

Chem 234 provides you with an opportunity to learn about the properties,syntheses, separation, purification, and identification of organic compounds. Thecourse consists of lecture sessions and laboratory sessions.

In lecture sessions you learn the theory and detailed background behind certainorganic experimental techniques.

In laboratory sessions you conduct experiments designed to introduce you to avariety of these experimental techniques. Chem 234 is also designed to provideyou with the opportunity to learn how to keep the records of scientific research in alaboratory notebook, a skill which is required in many scientific fields.

You are, of course, expected to perform the assigned experiments in thelaboratory, but you are also expected to understand the principles behind theseexperiments. Near the end of the course, you will be expected to carry out thechemical syntheses of organic compounds and determine the structures ofunknowns.

ExperimentsThe techniques and background material for each experiment will be presented inthe weekly lecture session. You must read the appropriate text and syllabusmaterial before coming to each lecture

You will perform the experiments only in your assigned laboratory period. Weexpect that you will come to each laboratory session well-prepared and ready touse your laboratory time efficiently. There are times when you may need to work ontwo different experiments in the same laboratory session, so you must plan ahead.If you miss a lab period for a valid reason (medical or a pre-approved absence),you may be able to do the experiments at another time (preferably that sameweek). However it is your responsibility to schedule these make-ups with your TAand with the Storekeeper. Unexcused absences cannot be made up and will bescored zero.

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Each new technique will be described to you in detail before you will have to use it,but thereafter you will be expected to be able to use that technique without anyfurther detailed directions. To do this, you must acquire not only good manipulativeskills in the laboratory but also a good sense about what a given procedureaccomplishes and when it should be used.

Occasionally, you may encounter difficulties with an experiment. If you areresponsible for this difficulty and require additional laboratory time and/or startingmaterial, a penalty of 10% of the grade for that experiment will be assessed. If,however, it is not your fault that you need extra time and/or material, no penalty willbe assessed.

Lab QuizThere is a on-line quiz associated with each experiment in WebCT. To receivecredit for the quiz it must be completed before the scheduled starting time of yourlaboratory section.

ChemNet LessonsChemNet lessons are available to aid in your understanding of the experiments andto make your laboratory work easier. Although you can work at these lessons anytime you wish, it is most helpful if you do the appropriate lessons shortly beforegoing to the laboratory. You will earn 2 points toward your grade for each organiclaboratory ChernNet lesson you complete.

In Chem 234 the ChemNet lessons are on the Internet. You access them throughWebCT.

To log onto ChemNet select the ChemNet icon in WebCT. Next you have to typeyour NetID and choose a secret password that you must remember. The passwordmay be the same as for your e-mail. You will be asked for this password each timeyou log onto ChemNet. The graded ChemNet lessons for Chem 234 are listedbelow (in the order you will want to complete them):

Melting PointsPhase DiagramsMixed Melting PointsRecrystallizationBoiling PointsMole FractionsB.P. of MixturesDistillation ExperimentFractional DistillationDistillation ColumnsExtractionsExtraction Experimentt-Butyl Chloride



Chemical TestsTry Known CompoundQualitative Unknown

Getting Help:There will be time at the end of each laboratory session to get help from yourteaching assistant. In addition, TAs are available in the Chemistry Learning Center,212 Chemistry Annex, Monday - Thursday afternoons to answer questions.

Missed Labs:For medical or true emergency reasons we will attempt to accommodate studentswho cannot carry out their experiments at the assigned times by scheduling them todo these experiments at other times. However, to receive credit for suchexperiments, the student must inform their own TA of the rescheduling andreschedule the experiment with the storeroom manager (469 Noyes Lab) at least 2days in advance of the make-up date. Such rescheduling will only be provided forsignificant medical reasons or emergency situations. More than one rescheduledlab per semester will require the written approval of the instructor in chargeof the course. Students will receive a grade of zero for labs not made-up and morethan one zero on a lab will almost certainly result in failure of the course.

GradingThe grading in Chem 234 is based upon the results of the ten experiments, the twoone-hour written exams, 10 on-line quizzes, and the 16 ChemNet lessons.

The semester of Chem 234 is divided into three parts. Part 1, Introduction toTechniques, emphasizes theory and principles. Most of the points in Part I areearned on a 50 minute written exam covering these topics.

Part II, Synthesis, emphasizes laboratory work. Most of the points in Part II areearned from the results (yields, purity, calculations) of the three experiments. PartIII, Identification of Organic Compounds, also emphasizes laboratory work, withmost of the points being based upon your ability to identify and support youridentification of an unknown organic compounds.

Near the end of the semester, the second (and last) 50 minute written exam willcover the theory and practice of the laboratory experiments in Parts 11 and 111,including the applications of spectroscopy.

The points assoicated with these activities are:Activity Points

Laboratory Work 10 for a total of 230 points 230On-line Quizzes 10@10 points each 10050 Minute Exams 2 @ 100 pts each 200



ChemNet Lessons 16 @ 2pts each 36Total 566

The grade distribution for Chem 234 will be approximately 15% A, 30% B, 50% C,and 5% D plus E. Therefore, an "average" student will receive the "average" gradeof C in this course. You must complete every experiment in order to receive at leasta grade of D.

Any requests for regrading of laboratory reports or quizzes must be submitted inwriting within one week of the day it is handed out in class. No requests will beaccepted after this time period. All laboratory reports to be regraded should besubmitted to your TA.

If you cheat on any lab (i.e., report false data for the melting points or gram yieldsof the samples you turn in), you will automatically receive a grade of zero for thatexperiment andlor an F grade for this course.

Your TA will check the melting point and gram yield of your samples.

On-line quizzes must be completed before the start of your scheduled laboratoryperiod.

Laboratory Notebooks and ReportsYour laboratory notebook is the complete and permanent record of your activities inthe laboratory. Your notebook should be patterned after the form discussed inChapter I of the textbook. All data, observations, etc., should be entered directlyinto the laboratory notebook during the laboratory session. As part of yourpre-laboratory preparation, you should enter the quantities and physical propertiesof all the compounds and solvents to be used for an upcoming experiment. Yournotebook will not be turned in each week, but it will be checked during the semesterby your TA.

Your laboratory report is different from your laboratory notebook. Your report is acomplete and readable summary of the experiment you have just performed. Thereport is written on a sheet of paper separate from your laboratory notebook. Eachlaboratory report is due one lab period after you finish the particular experiment.Laboratory reports should be turned in at the beginning of the laboratory session. Alate laboratory report incurs a penalty of 10% of the grade for that experiment. Noreport will be accepted more than two lab periods after it is due unless extenuatingcircumstances prevail.

Since your laboratory reports will be graded, you should write themlegibly, clearly, and in good English. The laboratory report should statea reference to the procedure followed and list any changes that weremade from the stated procedure. DO NOT copy the entire procedureinto your report, as it is not expected and is a waste of time. DO include



the following items:

(1) Balanced equations for the chemical reactions,

(2) Summaries of data and yields, including the appropriate calculations,

(3) Graphs or tables, if appropriate,

(4) A discussion of errors and their possible effects upon the results of theexperiment,

(5) Answers to all assigned exercises (see below),

(6) Anything else assigned, and

(7) Anything you feel is pertinent to a good summary of the experiment.




Chem 234 Check-In ProcedureYou will not be charged for stocking your drawer during this initial check of its contents. Afterthis, however, you will be charged for replacing any damaged or missing items. You MUSThave the contents of your locker checked by a TA or a storeroom manager upon yourtermination of enrollment in Chem 234 or your completion of this course. Failure to have yourlocker checked will result in a fine of ten dollars. This fine will be in addition to the charges thatwill be made for replacing any broken or missing equipment. Finally, you are responsible forthe cleanliness of your own work area. For safety reasons, keep it clean!

1. Remove the equipment in your drawer, and check it against the Equipment Liston the last page of the syllabus.

2. Return any extra equipment you find in your drawer to the storeroom manager in469 Noyes Lab.

3. Mark on the Equipment List any items you find broken or missing. Remember tocheck for "star" cracks in glassware. Make sure that your thermometer is notcracked, and that the 0-ring is inside the thermometer adapter. Also check to seethat the four indentions at the bottom of your distilling column are intact.

4. Bring your completed Equipment List to the storeroom manager in room 469Noyes Lab. Also bring him any repairable damaged equipment for replacement. Hewill replace your damaged equipment with good items and will provide you with anyitems you have found missing. Your drawer should now have a full set ofequipment as listed on the Equipment List.

5. Return all checked items to your drawer. Matches, rubber bulbs, and glassstirring rods should stay in your drawer.

6. Leave the Bunsen burner on the top of your desk. Leave the Thiele tube in theclamp provided for it above your work area. DO NOT put the Bunsen burner, Thieletube, or vacuum hoses in your locker. All ironware is to be kept in the bins at theends of the lab. If you use these items during a laboratory session, remember toreturn them to the proper bins at the end of the laboratory session. DO NOT putthem in your locker. All tubing (except that on the steam bath or Bunsen burner)and wire gauze should be kept in the boxes at the east and west ends of the lab.

To identify the names of equipment consult the display just inside the door or the equipment listshown below.

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Chemistry 234 equipment display in 464 Noyes Lab.

Chem. 234 Equipment List

1 Adapter, Bent, 105° 14/20standard taper joint

1 Adapter, Distilling, 14/20, w/10/18 Thermometer joint

1 Adapter, Teflon, Thermometer,10/18 w/ O-ring

2 Beaker, Griffin, w/spout, 30 mL




1 Beaker, Griff in, w/spout, 100 mL




1 Bulb, pipette, pure gum rubber

2 Clamps, i.e., Plastic, yellow, for 14/20 joint

2 Clips, Tubing, Steel (used to attach gum rubber hoses to glassjoints)

1 Column, Distilling, 14/20 standard taper joint.,10 x 130 mm,

1 Condensor, Leibig, 14/20 standard taper joint

1 Cylinder, pyrex glass, graduated, 10 mL



1 Cylinder, poly, graduated, 50 mL

2 Flask, Erlenmeyer, 25 mL




1 Flask, Filter, 125 mL&

1 Flask, Pear-shaped, 14/20 standard taper joint, 25 mL



1 Flask, Recovery, 14/20 standard taper joint, 25 mL



1 Funnel, Buchner, Porcelain, #2, 67 mm 01); Includes onerubber stopper w/ center hole

1 Funnel, Hirsch, Porcelain, 4/0, 55 mm OD

1 Funnel, Polyethylene, 31, 4" x 4"

1 Funnel, Powder, P.E., 65 x 15 mm

1 Funnel, Separatory, 250 mL,- Includes one each #22 glassstopper & teflon stopcock. (Note: TefIon stopcock has twoO-rings. One black rubber O-ring & one white teflon O-ring)

1 Glass rod, 9mm x 255mm



1 Holder, Test Tube

1 Rack, Test Tube

1 Spatula, Stainless Steel, double bladed

1 Stopper, Glass, 14/20 standard taper joint.

6 Test Tube, Pyrex, 13 x 100 mm

3 Test Tube, Pyrex, 25 x 150 Mm

1 Test Tube, Pyrex, 25 x 200 mm

1 Test tube, w/Side-arm, 25 x 200 mm

1 Thermometer, -100 to 260°C

1 Tube, Drying, Polyethylene

1 Wash bottle, Polyethylene, 250 mL

1 Watch Glass, Plain, 75 mm diameter






LABORATORY SAFETYRead Chapter 1, especially pp. 15-21, of the textbook before coming to your first laboratorysession. You will fill out the Safety-device Location Worksheet during your first laboratorysession.

The importance of safety precautions in a Chemistry laboratory cannot be overemphasized.

The following safety rules must be followed. Use common sense when working with chemicalsand laboratory apparatus. As safety is an integral part of this course, your TA will be gradingyou for compliance with these safety rules.

Laboratory Safety Rules

1. You must NOT be in the laboratory without a TA present. The laboratorysessions are four hours in length. You will not be allowed in lab after your labsession has ended.

2. Safety goggles for eye protection must be worn in the laboratory at all times.Prescription eyeglasses (even with safety lenses) do not provide adequate eyeprotection, especially from the sides. Therefore, you will be removed from thelaboratory if you are found without safety goggles covering your eyes. It is verystrongly recommended that you NOT wear contact lenses of any kind in thelaboratory. You should read the safety information on contact lenses and laboratoryaccidents posted outside the lab. Please check with your TA if you absolutely needto wear contact lenses. If you get anything in your eyes, wash your eyes thoroughlywith plenty of water and notify your TA immediately.

3. Shoes MUST be worn in the laboratory at all times. Sandals or perforated shoesare not permitted, as broken glass and spilled chemicals are constant hazards.

4. Shorts and short skirts (above the ankle) will NOT be allowed.

5. You MUST note the location of the fire extinguishers, safety showers, eyewashes, and first-aid kits in the laboratory, so that you will know where to obtainthese items if they are needed. You will fill out the Safety-device LocationWorksheet during your first laboratory session.

6. Many of the chemicals used in the laboratory experiments will be new to you.You should become acquainted with the properties of every new chemical you use.The Merck Index is a good source for finding the properties and toxicities of many

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organic compounds. All chemicals should be treated as though they are toxic.Compounds can enter the body by being absorbed through the skin, or by beinginhaled or ingested. Therefore,

(a) Keep vessels covered. Put the caps back on the solvent bottlesimmediately. Never evaporate solvents other than water into theatmosphere. Wipe up any spills immediately. In order to check for anodor, hold the sample about a foot away from your face and gently fanthe vapors towards your nose. Do not put anything in your mouth.

(b) You should use the gloves that are available. Keep your bench topclean! DO NOT rub your eyes or your face without first washing yourhands. If something does get into your eyes, remember to wash youreyes with plenty of water and notify your TA. You should protect yourclothing by wearing a laboratory apron. Always wash your handsthoroughly before leaving the laboratory session. If you have any cutsor scrapes, cover them with band-aids, etc., before coming to thelaboratory.

(c) To dilute acids, carefully and slowly add the concentrated acid to thewater, never the other way around. This avoids dangerous splattering."Do like you oughta, add acid to water".

7. Never heat a closed system! Always use boiling chips when heating any liquid,even water. When heating a test tube, never point it at yourself or at anyone else.Never heat flammable solvents (i.e., anything other than water) in an opencontainer with a Bunsen burner.

When you want to use a Bunsen burner, make sure that none of your neighbors isusing a flammable solvent. Light the match first, then turn on the gas while holdingthe match close to the top of the burner. Long hair must be tied back. Do not weargarments with floppy sleeves or loose wrist cuffs. Turn off the Bunsen burnerimmediately when you are finished with it.

8. Do not use cracked or chipped glassware. Examine your glassware for "star"cracks. Broken glassware should be replaced immediately with new glassware fromthe storeroom. Do not handle broken glass with your hands. Sweep it up, or use awad of toweling to grasp the pieces.

9. Only aqueous solutions (e.g., aqueous acids and bases) may be discarded downthe drain. Flush them down with plenty of water. Other waste materials, both liquidand solid, should be disposed of into the labeled waste containers located in thehoods. Broken thermometers should be put into jars located in the hoods. Ask yourTA to assist you in cleaning up any spilled mercury.

10. In the case of an accident (cuts, burns, reaction to a chemical, etc.), informyour TA immediately. A limited degree of first-aid is available in the storeroom,469 Noyes Lab. If you are seriously injured, you will be taken to the medical center.Report all accidents immediately.

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Your health is more important than your grade in Chem 234!

11. Never pour chemicals directly from the storage containers directly into yourreaction vessel.

12. Smoking, eating, and drinking are not permitted in the laboratory.

13. No pets are allowed in the laboratory.

14. No "horseplay" is allowed in the laboratory.

15. No radios are allowed in the laboratory.

A good perception of your surroundings is very important in a chemicallaboratory. This state of mind requires your full attention. Take care ofyourself and your neighbors. Immediately warn your neighbor if you seehim/her doing something dangerous. It is natural for you to feel somewhatconfused at times. Do not be shy to ask your TA or the storeroom managerfor guidance with the use of the laboratory equipment or for advice on safetymatters. Please respect the fact that other students must use the commonlaboratory equipment, such as the balances, melting point apparati, hoods,etc. Take care of this equipment, and clean up your messes immediately.

Safety and Emergency Equipment In 467 Noyes Lab

The Chem 234 laboratory sessions will be held in 467 Noyes Laboratory. This labcontains the following safety and emergency equipment:

Fire Blanket

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Fire Extinguisher

Overhead Shower

Safety shower with

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curtin.

Eye-Wash Faucets

Eye wash station

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Two drench hoses.

Fire Alarm

First Aid Kit

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Before you begin laboratory work in this course, you must complete the Safety device LocationWorksheet. Locate each of the items listed above and mark their locations on the Worksheetby using the symbols shown above. Indicate where your own area is located, and then indicatewhere the six nearest Eye-Wash Faucets are in relation to your work area.

In addition mark the location of the Eye-Wash station, the shower equipped with a curtain, andthe two drench hoses.

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You must wear appropriate clothing in the laboratory at all times. You MUST wear your safetygoggles over your eyes at all times in the laboratory! DO NOT wear loose or skimpy clothing(saris, neckties, shorts, halter-tops, overly large or ragged laboratory coats). DO wear closedshoes in the lab. DO NOT wear sandals or perforated shoes. Long hair must be tied back.

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Experiment 1: Melting Points (10 points)

I. Summary

Melting points are very useful in determining the purity of a compound. Throughout this classyou will measure the melting point of your products in order to assess purity. You will practicethis technique on a sample of benzoic acid.

Put open end of tube inthe sample.

Tape tube so samplefalls to the bottom of thetube.

Impure samples have lower melting points than pure solids. You can use this information todetermine the identity of an unknown through the mixed melting point method. You will begiven an unknown from the list below. By determining the melting point of your unknown, you

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will be able to narrow the choices to three, based on the melting point ranges. You will then mixyour unknown with EACH of the three possibilities. You can determine the melting point ofeach of the mixtures. In the two mixtures that contain two different compounds, you should seea drastic change in the melting point since the samples are not pure. One of the samples willcontain only one compound, and this should be reflected by the melting point.

Compound Melting Pointacetanilide 113-115 °C

p-aminobenzoic acid 188-189 °Ccamphoric acid 183-186 °C

trans -cinnamic acid 133-134 °Cmalonic acid 135-137 °Cp-nitrophenol 113-115 °C

resorcinol 110-113 °Csuccinic acid 187-189 °C

urea 133-135 °C

First obtain a sample of benzoic acid from your TA (about a spatula-tip). Grind the sample intoa fine powder, and take two melting points, one fast, one slow (2 °C/min). Obtain your unknownfrom the stockroom, and grind this sample if necessary. Take two melting points of your known(one fast, one slow). You should now be able to determine the three possibilities for the identityof your unknown.

Mix a spatula-tip of your unknown with a spatula-tip of each of the three possible compounds.These samples should be well mixed to ensure the best results. Take the melting points ofeach of the mixtures, and use this information to determine the identity of your unknown,

Samples of twocompounds for mixedmelting point.



Grind samples together.

III. Report

Your report should include the following:

1. Reference to the procedure with any changes noted

2. Data for melting points of benzoic acid

3. Data for melting points of unknown sample

4. Data for the three mixtures

5. Identity of your unknown

6. Interpretation of data and a short conclusion

You should measure the melting point with the Thiele tube at your bench or the electricallyheated melting point apparatus in the lab.

Thiele tube meltingpoint apparatus



Electrically heatedmelting pointapparatus

You should complete the web-based ChemNet tutorials on melting points before coming to thelab.




Experiment 2: Recrystallization (10 points)Summary

You will be learning several techniques for purification of organic compounds. One veryeffective way to purify solids is through recrystallization. In this experiment, you will be given animpure sample of benzoic acid that you will purify by recrystallization. You will also detenninethe melting point of the recrystallized benzoic acid to assess the purity.

Impure sample ofbenzoic acid.

Benzoic acid afterrecrystallization.

Procedure

The procedure for recrystallization is found in your text, page 97. You will make the followingchanges to the procedure:

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1. Scale up the procedure so that it accommodates 2 grams of benzoic acid.

2. Weigh the sample of impure benzoic acid before you begin recrystallization.

3. Skip the "Decoloration" section.

Heat the sample with enoughwater to dissolve all solublematerial.

Add more water if needed.

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Filter the hot solution toremove insoluble material

Boil off some of the water.

Use a boiling stick when youboil off the solvent.

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Be sure to use the GLASSpowder funnel for your hotfiltration rather than the plasticfunnel.

Crystals form as solution iscooled.

Cool to completecrystallization.

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Filter, wash, and dry theproduct.

Note: You will need a total of 40-5O mL of water for this experiment. If you add too much wateryou can boil some off after filtration.

Report Requirements

Your lab report should include the following:

1 . References to procedure with any changes noted

2. Weight of recrystallized benzoic acid

3. Percent recovery of benzoic acid

4. Melting point of recrystallized benzoic acid

5. Interpretation of data and short conclusion (discuss purity, recovery, and overalleffectiveness of recrystallization)

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Experiment 3: Fractional Distillation (15 points)Summary

Fractional distillation is a technique used to separate volatile compounds withboiling points that differ by less than 50° C. In this experiment, you will distill amixture of methanol (b.p. 65°C and water (b.p. 100°C). Using data obtained in thisexperiment, you will graphically demonstrate how head temperature changes withthe composition of the distillate.

Procedure

Obtain 60 mL of a sample of one of the methanol/water mixtures from the carboysin the lab. Record which sample you chose (A, B, or Q). Add the mixture and a fewboiling chips to a clean 100 mL round bottom flask. Set up the apparatus forfractional distillation as demonstrated in lab.

Use the Thermowell toheat the flask.

Plug it into the Variacon your bench.

Do not plug directly inthe wall outlet.

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Use a distilling columnto help separate themixture.

The thermometeradapter allows you toput the thermometerinto the distillingadapter.



Use joint clamps andhose clamps.

Here is the completedapparatus.

Have your set-up approved by your TA before you begin.

Begin heating the sample on a low setting and increase the temperature asneeded. Collect the distillate in a graduated cylinder. Record the head temperaturewhen you collect the first drop of distillate, and then record the head temperature atevery two milliliters of distillate collected. Stop the distillation when you haverecorded three readings at about 100°C, even if you haven't distilled all of thesample.

DO NOT heat the flask to dryness.



Report

Your report should include the following:

1 . References to procedure with changes noted

2. Table of recorded data (volume collected and head temperature)

3. Graph of distillation data: Make a plot with the head temperature on the y-axis and thevolume of distillate on the x-axis (see page 125 of your text). Draw an AVERAGE linethrough the data points. DO NOT simply connect the dots.

4. Summary table of data: Use your graph to determine the volume and boiling pointrange of each "fraction." Make a table that includes Fraction number, collected volume,and boiling range.

5. Interpretation of data and conclusion, including the methanol/water ratio of yoursample

Tutorials

You should work the web-based ChemNet tutorials on distillation before going tothe lab.




Experiment 4: Extraction (20 points)Summary

Extraction is a technique used to separate and/or purify compounds. In thisexperiment, you will be separating a mixture of anthracene, p-nitroaniline, andbenzoic acid into the individual components based on their differing solubilities inimmiscible phases.

Mixture of anthracene,p-nitroaniline, and benzoic acid.

Purified benzoic acid

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Purified anthracene

Purified p-nitroaniline

Prelab

BEFORE class, prepare a flow chart that outlines every step of the experiment. Theflow chart should show a branch point at every extraction step (including isolation ofthe three compounds), and you should note which compounds are in each layer ateach step. You must have this flow chart completed before you will be allowed tobegin the experiment,and the flow chart will be handed in with your lab report.

Procedure

Obtain a mixture of benzoic acid, p-nitroaniline, and anthracene. Weigh the mixture,and then dissolve the mixture in 75 mI, of methylene chloride. If some solid doesn'tdissolve after several minutes of stirring, filter the solution. Add the solution to theseparatory funnel and proceed through the following steps:



First Period:

1 . Add 50 mL of 3M HCI to the separatory funnel. Shake and vent the funnel asdescribed in the textbook readings.

Be sure to vent the separatory funnel to avoid pressure build up. If you get hydrochloricacid on your skin be sure to wash with large amounts of water. Contact your TA forassistance.



2. Allow the layers to separate in the funnel. Drain the bottom layer into a flask labeled"organic," and pour the top layer into a flask labeled "acidic extract"

3. Return the organic layer to the separatory funnel, and repeat steps 1 and 2. Add thetop layer from this extraction to the flask labeled "acidic extract".



4. Place the organic extract into the separatory funnel, and add 50 mL of 3M NaOH.Shake and vent the separatory funnel as before. If you get sodium hydroxide solution onyour skin be sure to wash with large amounts of water. Contact your TA for help.

5. Allow the layers to separate. Drain the bottom layer into a flask labeled "organic," andpour the top layer into a flask labeled "basic extract."

6. Return the organic layer to the separatory funnel, and repeat steps 4 and 5. Add thetop layer from this extraction to the flask labeled "basic extract."

7. Cool the ACIDIC EXTRACT in an ice bath. Basify the ACIDIC EXTRACT with 6MNaOH (calculate how much you need). Check the pH of the solution with pH paper tomake sure it is BASIC. Filter the resulting precipitate by vacuum filtration. Place the solidon a piece of filter paper, and allow it to air dry until the next lab period.

USE CAUTION IN HANDLING THE SODIUM HYDROXIDE.

8. Cool the BASIC EXTRACT in an ice bath. Acidify the BASIC EXTRACT with 6M HCl.Check the pH of the solution with pH paper to make sure it is acidic. Collect the resultingsolid by vacuum filtration. Place the solid on a piece of filter paper and allow it to air dryuntil the next lab period.

9. To the ORGANIC layer, add a few spatula tips of Na2S04 to dry the organic layer.Allow the solution to stand for 10 minutes.

10. Filter the solution through fluted filter paper into an Erlenmeyer flask. Evaporate themethylene chloride using the apparatus that will be demonstrated in lab.



Second Period:

1. Obtain weights of benzoic acid, p-nitroaniline, and anthracene and melting points ofbenzoic acid and p-nitroaniline.

2. Place all solids in tared, labeled vials, and give them to your TA.

Report Requirements

Your report should contain the following:

I . Reference to procedure with changes noted

2. Flow chart described above

3. Weights of all three solids

4. Melting points of benzoic acid and p-nitroaniline (both weights and melting pointsshould be reported in tabular form)



5. Interpretation of data and conclusion

-How pure are the extracted compounds?

-How could you purify them further?

-What was the composition of the original mixture, i.e., the ratio of benzoicacid: p-nitroaniline: anthracene?

- recovery




Experiment 5: Preparation of2-chloro-2-methylpropane (20 points)

Summary

In the experiment, you will be preparing 2-chloro-2-methylpropane from 2-methyl-2-propanolvia an SN1 reaction.

Procedure

You will follow the procedure from the text (pages 389-390). Note that you will be using2-methyl-2-propanol instead of 1-methyl-2-butanol. However, all other reagents remain thesame. You should double all quantities listed in the procedure.

Shake the t-butyl alcohol with HCl.

Be sure to vent the separately funnel to avoidpressure build up.

If you get hydrochloric acid on your skin washimmediately with large amounts of water.Contact your TA for assistance.

Separate, wash, and dry the t-butyl chloride.

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The crude t-butyl chloride is washed to removeexcess acid.

Add the sodium bicarbonate solution slowly toavoid rapid formation of CO2 as shown here.

Setup for distillation ofthe t-butyl chloride.

Collect the product in acooled, tared container.



Use joint clamps on thecondenser and hoseclamps on the waterlines.

Post-lab Questions

1. Washing the crude 2-chloro-2-methylpropane with aqueous sodium bicarbonateresulted in gas evolution. Write a balanced equation for this reaction.

2. Could anhydrous NaOH be used to dry the 2-chloro-2-methylpropane instead ofNa2SO4?

3. Explain why 1-butanol does not react with HC1 under the conditions used in thisexperiment.

Report Requirements


1 . Reference to the procedure with changes noted

2. Equation of the reaction showing structures of reactants and products. Below eachreactant, list the molecular weight, and amount used in grams (or mLs) and moles. Beloweach product, list the theoretical yield in grams and moles.

3. Mechanism of the reaction: use arrows to show electron movement; include allintermediates and side reactions

4. Calculation of the theoretical yield

5. Weight of product



6. Boiling range of the product


8. Answers to post-lab questions




Experiment 6: Preparation of methylbenzoate(40 points)

I. Summary

In this experiment you will prepare methylbenzoate by reacting benzoic acid withmethanol using sulfuric acid as a catalyst. Since this is a reversible reaction, it willreach an equilibrium that is described by the equilibrium constant, Keq .

In this experiment, you will isolate the product, methyl benzoate and any unreactedbenzoic acid. Using this data, you will calculate the equilibrium constant for thereaction as described in part III.

II. Procedure

First Period

Obtain a 10g (0.082 mol) sample of benzoic acid fromthe storeroom (weigh the benzoic acid to obtain anexact weight before you begin). Add to it 0.62 mol ofmethanol in a 100 mL round-bottomed flask.

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Cautiously, add 3 mL concentrated H2S04 down theside of the flask. After gently swirling the contents ofthe flask, attach a reflux condenser and reflux themixture for about 60 min.

Sulfuric acid causes acid burns on the skin. If you getsome on your skin be sure to wash with large amountsof water. Contact your TA!

Allow the solution to cool. Add 50 mL of water to a separatory funnel, then add thecontents of the flask. The flask should then be washed with 40 mL ofdichloromethane (CH2C2) and the washings transferred to the separatory funnel.Use the separatory funnel to extract the ester into the CH2Cl2 (organic) layer. Allsequentially with 25 mL water and 25 mL 0.6M sodium bicarbonate* (Caution,CO2 will be given off with effervescence). After shaking and venting the funnel,remove the sodium bicarbonate layer and test to see if it is basic. Then wash theorganic layer with NaCl (salt) solution, separate the organic layer and dry withanhydrous magnesium sulfate. Remove theMgS04by gravity filtration, andconcentrate the solution using the same apparatus used to remove CH2Cl2 fromanthracene in Experiment 4.

*The aqueous layer from the sodium bicarbonate wash should be acidified withconcentrated HCl The unreacted benzoic acid should precipitate. Remove thesolvent by vacuum filtration. Collect and dry the solid benzoic acid and let it air-dryin your drawer until the next lab period.

Second Period

Distill the crude methyl benzoate (b.p. 199°), collecting anything that boils between170°C and 200°C. Weigh the sample of methyl benzoate and determine the yield.Weigh the sample of recovered benzoic acid. Place both samples in labeled vials,and give them to your TA.



Caution:

1. Methanol is flammable and toxic 2. Dichloromethane is toxic

3. Handle concentrated H2SO4 and HCl with great care

4. Vent the separatory funnel frequently after swirling and subsequent shaking.CO2, gas is evolved and will build up pressure in the funnel.

III. Calculation of the Equilibrium Constant, Keq.

Calculate a value for the equilibrium constant Keqbased upon your weight ofrecovered benzoic acid. In addition, calculate the percent yield of your synthesisbased upon the amount of starting benzoic acid used, and another percent yieldbased upon the amount of benzoic acid that actually reacted (as determined by theweight of recovered benzoic acid).

Calculation of the Equilibrium Constant Keq:

Since the volume of the reaction mixture is the same for each component, we canuse moles instead of molarities as the units in our Keq expression. Let Bi = initialmoles of benzoic acid, let Mi = initial moles of methanol, and let X = final moles of



methyl benzoate produced at equilibrium.

Based upon the stoichiometry of equation 1, we can conclude three things about X,namely that X = final moles of water produced at equilibrium, X = moles of benzoicacid consumed when equilibrium is established, and X = moles of methanolconsumed when equilibrium is established. Using our definitions, equation 2becomes:

We know Bi and Mi. All we need to do before we can calculate Keq is to Put X interms of something known, like the amount of benzoic acid recovered. Let Bf = finalmoles of benzoic acid present at equilibrium. Thus Bf = Bi - X, or X = Bi - Bf.Substituting(Bi - Bf) for X in equation 3 gives:

We can now calculate Keq by entering the appropriate values of the moles ofbenzoic acid used (Bi), the moles of methanol used (Mi), and the moles of benzoicacid recovered (Bf) into equation 5.

Calculation of the % Yield based upon initial amount of benzoic acid used:

Let E = moles of methyl benzoate ester obtained. Note that this calculation is validonly if benzoic acid is the limiting reagent.

Calculation of the % Yield based upon amount of benzoic acid that is consumed:



IV. Post-lab Questions

1. How is sulfuric acid involved in the formation of methyl benzoate?

2. Write a balanced equation for the formation of ethyl acetate from ethanoland acetic acid.

3. Using K=3.0, calculate the number of moles of methyl benzoate whichcould be formed from 0. 1 mol of benzoic acid and 0.3 mol of methanol.

V. Report Requirements

Your lab report should contain the following information:

1 . Reference to procedure with any changes noted

2. Equation of the reaction showing structures of reactants and products.Below each reactant, list the molecular weight, and amount used in grams (ormLs) and moles. Below each product, list the theoretical yield in grams andmoles.

3. The complete mechanism showing all intermediates and arrows todemonstrate electron movement

4. Flow chart for the isolation of methyl benzoate and unreacted benzoic acid

5. Weight of recovered benzoic acid

6. Weight and boiling point of methyl benzoate

7. Calculations

a. percent yield based on amount of benzoic acid with which youstarted

b. percent yield based on amount of benzoic acid consumed

c. equilibrium constant








Experiment 7:Preparation of methyl-m-nitrobenzoate (25 points)

I. Summary

In this experiment, you will synthesize methyl-m-nitrobenzoate from methylbenzoate via electrophilic aromatic substitution. The isolated product will be purifiedby recrystallization, and purity will be determined from the melting point.

II. Procedure

Bring a clean, dry 25 x 150 mm test tube to the storeroom manager and trade it infor a 6.2 mL (6.8 g, 0.050 moles) sample of methyl benzoate (weigh the samplebefore you begin to obtain an exact weight). Place 14.5 mL (26.7 g) of concentratedsulfuric acid in a 125 rnL Erlenmeyer flask, cool it to 0 °C in an ice/water bath, thenadd all of the methyl benzoate with swirling.

Separately, prepare a mixture of 5.0 ml- (9.2 g, 0.094 moles) of concentratedsulfuric acid and 5.0 mL (7.1 g, 0. 113 moles) of concentrated nitric acid. Cool thenitric acid in an ice bath and then very slowly add the sulfuric acid keeping themixture cold.

Be very careful in handling the concentrated sulfuric acid and nitric acid. If you getacid on you be sure to wash with large amounts of water and contact your TAimmediately for assistance.

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When it has cooled, add this coldacid mixture dropwise over 5minutes to the methyl benzoatesolution, which is kept swirling inthe ice bath.

After the addition is complete,allow the reaction mixture to standat room temperature for anadditional 10 minutes, swirling itoccasionally.



Pour the mixture, with stirring,over about 150 cc of crushed ice.

Collect the solid precipitate bysuction filtration, and wash itthoroughly with water to removeany traces of acid.

Finally, wash the product twicewith 5 mL portions of ice-coldmethanol. Recrystallize yourproduct from a small amount ofmethanol.

Collect the crystals by vacuum filtration, and allow the product to air dry in yourdrawer until the next lab period. Obtain the weight and melting point of your dryproduct. Give your sample to your TA.

III. Post-lab Questions

1. Draw all resonance structures for the nitration of methyl benzoate occurring at the



ortho, meta, and para positions. Be sure to include all charges.

2. Circle any resonance structures which demonstrate why the ortho-para positions areunfavorable sites for nitration.

IV. Report Requirements

Your report should contain the following information:

1. Reference to the procedure with changes noted

2. Equation of the reaction showing structures of reactants and products. Below eachreactant, list the molecular weight, and amount used in grams (or mLs) and moles. Beloweach product, list the theoretical yield in grams and moles

3. Mechanism of the reactions showing the structures of intermediates and arrows todemonstrate electron movement

4. Experimental yield and percent yield (show calculations)

5. Color of product

6. Melting point of product






Experiment 8: Dehydration of CyclohexanolI. Summary

In this experiment, you will synthesize cyclohexene via acid-catalyzed dehydrationof cyclohexanol. This reaction will be carried out by heating the components andcollecting impure product. A second distillation will be necessary to purifycyclohexene. Purity will be determined by the boiling point of the collected product.The product will be tested for unsaturation using the Baeyer test.

II. Procedure

Bring a clean, dry 25 x 150 mm test tube to the storeroom manager, and trade it fora sample of cyclohexanol. Obtain a weight or volume for the sample (around 14.2gor 15 mL). Be sure to use the mass of your sample for all of your calculations. Intoa 50 mL round bottom flask, add the cyclohexanol, 9 M sulfuric acid (7.5 mL), and afew boiling chips. Mix the contents of the flask with gentle swirling.

Equip the flask for fractionaldistillation (see experiment 3).

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Use a heating mantle withsand to heat the distillationflask.

Use an erlenmeyer flask as the collection vessel, and cool it in an ice bath duringthe distillation. Heat the reaction mixture, and collect all distillates while maintaininga head temperature in the range of 80-85 °C. Discontinue the reaction once about 5mL remains in the distillation flask.

Add several spatula-tips full ofpotassium carbonate to the crudeproduct in the Erlenmeyer flask. Swirlthe mixture occasionally over a 10-15minute period, and add morepotassium carbonate IF the liquidremains cloudy.

Thorough drying is very important (why?).Transfer the product to an 25 mL round bottomedflask by decanting or using a pipet.



Add a few boiling stones to theflask, and purify the product bysimple distillation. Use a taredvial as a receiver, and cool thereceiver in an ice bath.

Collect distillate with a head temperature between 80-85 °C. Obtain a weight ofyour purified product. Note: If product is cloudy, add several spatula-tips full ofpotassium carbonate to the vial, and transfer the dried product to another tared vialby pipet before weighing.

Bayer Test for Unsaturation:To test your product for unsaturation, follow the procedure on pages 653-654 ofyour lab text for the Baeyer test. Perform both the test and the blank.

III. Report Requirements

Your report should contain the following information:1. Reference to procedure with changes noted.2. Equation of the reaction showing structures and products. Below each reactant,list molecular weight, amount used in grams (or mL) and moles. Below eachproduct list the molecular weight and theoretical yield in grams and moles.3. Mechanism of the reaction showing structures of intermediates and arrows todemonstrate electron movement.4. Experimental yield and percent yield (show calculations)5. Weight of product.6. Boiling point range of product.7. For the Baeyer test, include both the mechanism of the reaction and your resultsfor cyclohexene and the blank.8. Interpretation of data and conclusions






Experiment 9:Preparation of trans-p-Anisalacetophenone

(25 points)I. Summary

In this experiment, you will be preparing trans-p-anisalacetophenone (m.p. 77-78°) from p-anisaldehyde andacetophenone via a crossed aldol condensation. The product will be purified by recrystallization, and puritywill be assessed by taking the melting point of the product.

II. Procedure

Follow the procedure found on pages 499-500 in your text (omit the "Analysis" portion of theprocedure. You will need to scale the procedure to six times that listed in the text. Take a clean,dry 25 x 150 mm. test tube to the storeroom manager and trade it in for a sample ofp-anisaldehyde. Weigh the sample before you begin the experiment, and adjust the amount ofacetophenone accordingly. Once you have obtained the recrystallized product, allow the productto air-dry in your drawer until the next lab period. Obtain the weight and melting point.

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Locate starting material

Measure reactants

Mix



Let stand

Filter crude product

Recrystallize



Purified product

III. Report Requirements


1. Reference to procedure with changes noted.

2. Equation of the reaction showing structures of reactants and products. Below each reactant,list the molecular weight, and amount used in grams (or mLs) and moles. Below each product,list the theoretical yield in grams and moles.

3. Mechanism of the reactions showing the structures of intermediates and arrows todemonstrate electron movement

4. Mass of product

5. Percent yield (show calculations)

6. Melting point of product (include literature melting point)

7. Interpretation of data and conclusion, including detailed error analysis




Experiment 10: Identification of an Aldehyde,Amine, Alcohol, or Ketone (45 points)

I. Summary

In this experiment you will be given an unknown that is either an aldehyde, ketone,amine or alcohol. The possible unknowns are listed in tables in the lab. You will begiven IR and NMR spectra to help you determine the functional group and structureof your compound. You will also obtain the boiling point or melting point of yourcompound, perform classification tests, and make a derivative.

II. Procedure

The week before this experiment begins, you will receive IR, 1H NMR, and 13CNMR spectra of your compound.

BEFORE the first day of this experiment, make a tentative functional groupassignment. You do not need to determine the structure of the unknown beforeclass, but you will need to analyze you spectra for structural information at somepoint during the course of the experiment. During the class periods assigned forthis experiment, do the following in the order listed:

1. Distill your unknown, if it is a liquid, to obtain aboiling point of the pure compound.

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You may also use this procedure todetermine the boiling point. Set up anapparatus for simple distillation. Inthis experiment, however, you will notactually distill your unknown. Useyour 25mL pear-shaped flask as adistillation flask. You will insert thethermometer all the way into the flask,so add enough of your unknown tothe distillation flask to completelycover the mercury bulb of yourthermometer.

Heat the flask until the unknown boils.You should record the boiling point asthe temperature at which thethermometer stabilizes.

If your unknown is a solid, take a melting point.

To obtain a boiling (or melting) point range, subtract 10°C from theobserved temperature to get a lower limit, and add 10° to the observedtemperature to get an upper limit.

2. Perform all three of the following classification tests.

You should first perform these tests on the provided known compounds forcomparison.

A. DNP - follow theprocedure on pages642-643 of your book.



B. Ceric nitrate test -follow the procedure onpage 667 of your text.

C. Test for pH - If your compound is water-soluble, use pH paper totest an aqueous solution of your unknown. An amine, since it is basic,will have a high pH. If your unknown is not water-soluble, dissolve theunknown in an ethanol-water mixture, and test the pH.

3. Make a derivativeOnce you have determined the functional group present inin your unknown, choose the appropriate derivative from the list below:

Aldehyde/ketone: 2,4-DNP (pg 642-643)Alcohol: 3,5-dinitrobenzoate (665, Method A, see Note 1 for amounts ofreagents)Amine: benzenesulfonamide (pg 678) or benzamide (pg 677-678)

III. Lab Report Requirements

Your lab report (due the day scheduled for check-out) should contain the following:1. Reference to the procedure of EACH chemical test and the derivative2. Melting/boiling point of the unknown3. Results of each chemical test and your interpretation of the results4. Data table for 1H NMR (see example)5. Data table for 13C NMR: For each relevant peak, report the chemical shift andassignment.6. Data table for IR (assign bands above 1500 cm-1): For each band, report position(in wavenumbers), a description of the band (strong, medium, or weak; sharp or



broad), and your interpretation7. Type of derivative and the melting point (include the reference melting point)8. Identification of the unknown with a THOROUGH explanation of how you arrivedat this conclusion

Notes:1. Preparation of the 3,5-dinitrobenzoate derivative (amounts):0.5g 3,5-dinitrobenzoylchloride (this will be preweighed and available fromthe storeroom)1.5mL of your unknown alcohol20 drops of pyridine (Caution! Pyridine should be used in the fume hoodsince it has a VERY unpleasant odor. Do not pour pyridine orfiltrates containing pyridine down the drain)

EXAMPLE 1H data writeup

Spectrum



Label hydrogens

Make table




Chem 234 Check-Out ProcedureAny student who fails to be checked out of the lab by a TA or by a storeroom manager will becharged with a fine of ten dollars. This fine is assessed in addition to the charges that are madeto replace any broken or missing equipment.

1. Remove all equipment from your drawer and wash each item with Tetrox and water.

2. Place new blotter paper lining in your drawer.

3. Check your equipment against the Equipment List. Return any extra equipment to thestoreroom and replace any missing or broken items with new ones from the storeroom.

4. Place all ironware (except the metal stand) in the bins at the ends of the lab.

5. Place all tubing (except that on the steam baths and Bunsen burners) and wire gauze intheir proper storage boxes located at the east and west ends of the lab.

6. All matches, rubber bulbs, and stirring rods should be left in the drawer.

7. Leave the rubber stoppers on the Hirsch and Buchner funnels. Throw out any corkstoppers.

8. Make sure that the four indentations at the bottom of your distilling column are intact.

9. Make sure that your thermometer is not cracked and that the O-ring is still inside thethermometer adapter.

10. Remove the calcium chloride from inside the drying tube.

11. Remove any stopcocks and stoppers from the separatory funnels. Tie them to thefunnels with string.

12. Place all the cleaned equipment back into your drawer. Your drawer should now havea full set of equipment as listed on the Equipment List.

13. Sign the equipment list (pg. 24) and have your TA sign the equipment list. Take thislist to Mike Eubanks (room 469) to receive your breakage card.

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