SECTION 1
TABLE OF CONTENTSIntroduction
Laboratory Safety Guidelines
Safety Declaration Form
Chemistry Laboratory Report Guidelines
Laboratory Note Books : Pre Laboratory preparation
Experiment
1. Synthesis and Characterization of Alkane, Alkene and Alkyne
(Saturated and Unsaturated Hydrocarbon)
2. Recrystallization of benzoic acid
3. Conversion of ethyl alcohol to ethyl acetate
4. Saponofication of fat: soap production
INTRODUCTION
This module provides guidelines for Laboratory safety guidelines, Safety declaration form, Laboratory report format, Laboratory note books and Laboratory manual for subject of Organic Chemistry (CLB 10302).
The main purpose of this module is to compile all necessary information regarding laboratory component in one module.
This module contains five sections. Section 1 provides a description of the laboratory guidelines and safety declaration form. It is COMPULSORY for student to understand all those guidelines and submit safety declaration for recording purposes. Section 2 is laboratory report guidelines containing all requirements such as format and arrangement in order to produce good quality of laboratory report. Section 3 is guidelines for preparation of laboratory notes book as a pre-laboratory preparation. Section 4 is compilation of laboratory manual that will provide student practical guidelines in organic chemistry.There may be shortcoming which we had overlooked but hopefully these should not hinder the process of enhancing laboratory skill.
SECTION 1
LABORATORY SAFETY GUIDELINES
General Guidelines
1. Conduct yourself in a responsible manner at all times in the laboratory.
2. Be familiar with your lab assignment before you come to the lab. Follow all written and verbal instructions carefully. If you do not understand a direction or part of a procedure, ask the instructor before proceeding.
3. No student may work in laboratory alone. The lab instructor or co-coordinator grant exceptions on a case by case basis.
4. When first entering a laboratory, do not touch any equipment, chemicals or other materials in the laboratory area until you are instructed to do so.
5. Do not eat, drink beverages or chew gum in the laboratory. Do not use laboratory glassware as containers for food or beverages.
6. Smoking is not allowed in any indoor area.
7. No music allowed in the laboratory. Radio (including walkman) and other entertainment devices are not permitted.
8. No cellular phone is allowed in this laboratory.
9. Perform only those experiments authorized by the instructor. Never do anything in the laboratory that is not called for the laboratory procedures or by your instructor. Carefully follow all instructions, both written and oral. Unauthorized experiments are prohibited.
10. Observe good housekeeping practices. Work areas should be kept clean and tidy at all times.
11. Horseplay, practical jokes, and pranks are dangerous and prohibited.
12. Always work in a well-ventilated area.
13. Bring only your laboratory instructions, worksheets and report to the work area. Other materials (books, purses, backpacks, etc) should be stored in the cabinet.
14. Know the locations and operation procedures of all safety equipment including the first aid kit, eyewash station, safety shower, spill kit and fire extinguisher.
15. Be alert and proceed with caution at all times in the laboratory. Notify the instructor immediately of any unsafe condition you observe.
16. Label and equipment instructions must be read carefully before use. Set up and use the prescribed apparatus as directed in the laboratory instructions provided by your instructor.
17. Experiments must be personally monitored at all times. You will be assigned a laboratory station at which to work. Do not wander around the room, distract other students or interfere with laboratory experiments or others.
18. Write your name and equipment use every time you come in to the laboratory in the log book.
19. Defeating safety devices or using equipment in a manner other than that which is intended will be grounds for dismissal from the lab.
Clothing
1. Safety goggles and safety jacket must be worn whenever you work in lab.
2. Gloves should be worn whenever you use chemicals that cause skin irritations or need to handle hot equipment.
3. Mask should be worn every time you prepare the chemicals.
4. Safety shoes and hard hat should be worn at all times while in the laboratory.
5. Contact lenses should not be worn in the laboratory unless you have permission from your instructor.
6. Dress properly during a laboratory activity.
7. Long hair, dangling jewelry and loose or baggy clothing are a hazard in the laboratory. Long hair must be tied back and dangling jewelry and loose or baggy clothing must be secured.
8. Sandal, open-toed shoes, high heels or shoes with holes in the sols will not be worn in the lab.
9. Short and skirts are not permitted.
10. Instructor and laboratory assistant have a right dismiss to you from the laboratory if they found that you are not wearing proper safety clothing.Handling Chemicals
1. Treat chemicals with respect and understand the chemicals you are using with Material Safety Data Sheet (MSDS). The MSDS are available in the analytical room.
2. All chemicals in the laboratory are to be considered dangerous. Do not touch, taste or smell any chemical unless specifically instructed to do so.
3. Check the label on chemical bottles before removing any of the contents. Take only much chemical are you need. Smaller amounts often work better than larger amounts.
4. Label all containers and massing papers holding dry chemicals.
5. Never return unused chemicals to their original containers.
6. Never use mouth suction to fill a pipette. Use pipette bulb or pipette filler.
7. Acids must be handled with extreme care. Always add acids slowly to water, with slow stirring and swirling, being careful of the heat produced, particularly with sulfuric acid.
8. Handle flammable hazardous liquid over a pan to contain spills. Never dispense flammable liquids anywhere near a flame or source of heat.
9. Never take chemicals or other materials from the laboratory area.
10. Take good care when transferring acids and other chemicals from one part of the laboratory to another. Hold them securely and in the method demonstrated by the instructor as you walk.
11. All wastes generated during the course of an experiment must be disposed of according to the lab instructors directions.
12. Never mix chemicals in sink drains.
13. Sinks are to be used only for water and those solutions designated by the instructor.
14. Solid chemicals, metals, matches, filter paper, and all other insoluble materials are to be disposed of in the proper waste containers, not in the sink.
15. Checks the label of all waste containers twice before adding your chemicals waste to the container.
16. Cracked or broken glass should be placed in the special container for broken glass.
17. Keep hands away from your face, eyes, mouth and body while using chemicals. Wash your hands with soap and water after performing all experiments.
Personal Hygiene
1. Wash hands before leaving the lab and before eating.
2. Gloves should be removed before leaving the lab, using telephones, or entering common areas.
Accidents and Injuries
1. Report any accidents (spill, breakage, etc) or injury (cut, burn, etc) to the instructor immediately, no matter how trivial it may appear.
2. If you or your lab partners are hurt, immediately tell to the instructor.
3. If a chemical should splash in your eye(s), immediately flush with running water from the eyewash station for at least 20 minutes. Notify the instructor immediately.
4. Spills should be cleaned up immediately.
Handling Glassware and Equipment
1. Inserting and removing glass tubing from rubber stopper can be dangerous. Always lubricate glassware (tubing, thistle tubes, thermometer, etc) before attempting to insert it in a stopper. Always protect your hands with tower or cotton gloves when inserting glass tubing into, or removing it from a rubber stopper.
2. When removing an electrical plug from its socket, grasp the plug, not the electrical cord.
3. Hands must be completely dry before touching an electrical switch, plug or outlet.
4. Examine glassware before each use. Never use chipped or cracked glassware.
5. Never use dirty glassware.
6. Do not immerse hot glassware in cold water; it may shatter.
7. Report damaged electrical equipment immediately. Look for things such as frayed cords, exposed wires and loose connections. Do not use damaged electrical equipment.
8. If you do not understand how to use a piece of equipment, ask the instructor for help.
9. Be careful when lifting heavy objects. Lift comfortably, avoid unnecessary bending, twisting, reaching out, and excessive weights, lift gradually and keep in good physical shape.
10. Do not transfer a glassware form one laboratory to another without permission from instructor.
Heating Substances
1. Do not operate a hot plate by yourself. Take care that hair, clothing, and hands are a safe distance from the hot plate at all times. Use of hot plate is only allowed in the presence of the teacher.
2. Heated glassware remains very hot for a long time. They should be set aside in a designated place to cool, and picked up with caution. Use tongs or heat protective gloves if necessary.
3. Never look into a container that is being heated.
4. Do not place hot apparatus directly on the laboratory desk. Always use an insulated pad. Allow plenty of time for hot apparatus to cool before touching it.5. If leaving a lab unattended, turn off all ignition sources and lock the doors.
Ended the Experiments
1. At the end of the laboratory sessions, you should;
a. Shut-off main gas outlet
b. Turn-off the water inlet
c. Desk top, floor area and sink are clean
d. All equipment is cool, clean and arranged
2. All equipment use should be flushed using deionized water.The Dean/Head of Campus
Universiti Kuala Lumpur
Malaysian Institute of Chemical and Bioengineering Technology
Lot 1988, Vendor City Industrial Area
Taboh Naning, 78000 Alor Gajah
MalaccaDear Sir,SAFETY DECLARATION
I ... ID No . declare that I have read and understood the safety rules and regulations in UniKL MICET. I hereby agree to abide by all the rules and regulations stated in the safety guidelines.
2. I hereby understood the contents and will disciplinary action will be taken against me, if I do not abide by the stated rules.
3. I am fully responsible for all my actions during laboratory sessions.
Thank you.
Yours faithfully,
.
Name:
Matrix No:
Subject:
Date: SECTION TWO
Chemistry Lab Report FormatYou should type your lab report, but you may draw or write by hand any tables, diagrams, or chemical equations as long as you do it neatly. Make sure that you check your document for any spelling errors. Each lab report is worth 100 points.You should also read the student handbook on the subject of plagiarism. Your data and observations will be similar, but your interpretations should not be written identically. You may not copy another student's lab report in part or in its entirety. If you are found guilty of this infraction, you and the person from whom you copied will both lose points. In extreme cases or repeated offenses, both students may receive a zero for the lab.
Title Use a separate title page. Include the title of the experiment, YOUR NAME, and the date. Also clearly indicate the name(s) of your lab partner(s).
Purpose Write a few sentences describing what you are supposed to learn by doing the experiment. You might write about learning the lab procedures themselves. Do not just copy word for word from the lab handout.
Materials
List the chemicals and equipment needed to perform the experiment.
ProcedureBriefly list or summarize the procedure. Again, DO NOT COPY DIRECTLY from the lab handout. Use your own words OR you may simplify it by drawing a flow chart.
Data / ResultInclude any data, qualitative and quantitative, that you collect. This includes any observations. You should include the proper units with any numbers, as well as use the proper number of significant figures based upon the lab equipment used. Remember, read the last known place and estimate one more digit. DO NOT place any calculations or data analysis in this section. It may be a good idea to reproduce here any data tables that you completed during the lab.
Data Analysis / Result AnalysisHere is where any calculations or graphs are placed. Also show how you arrive at identifying any unknowns. Make sure that your graphs have titles, labeled axes with units, and legends.
ConclusionsThis section is the most important one. Include the following: Percent error Sources of error (Don't just say that any errors were the fault of the equipment. Also don't use the generic excuse that you might have misread the measurements.) Identify any unknowns Answer the questions, "What did you learn?" "Did I accomplish the purpose?""How would I improve the experiment next time?"
References Write down any sources such as your textbook, the Internet, electronic encyclopedia, books, etc. that you used.
Post laboratory question Here is where you attach any material that you think is pertinent to the lab report. Also answer any questions here that are in the lab report. You do not have to re-write the questions, but label and number them appropriately. SECTION THREE
Laboratory Note bookYou are required to use a notebook in CLD 10302 Lab to record all primary data and observations. You should prepare your notebook before coming to lab by:-
1. Writing the title of the experiment on a new page.
2. Writing the objectives of the experiment.
3. Summarizing relevant information from the manual, like the method; by drawing a flow chart for each experiment.Guidelines to be followed:
Always bring your notebook with you to lab. You will be graded on the completeness of your preparation for the current experiment. Take your notebook during laboratory hours and record all values directly in it not on loose scraps paper.
Write down all observations if necessary dont rely on your memory.
If you make a mistake in your notebook, simply draw a solid line through the error and write the correction nearby.
SECTION FOUR
EXPERIMENT 1
Synthesis and Characterization of Alkane, Alkene and Alkyne
(Saturated and Unsaturated Hydrocarbon)
OBJECTIVE
1. To synthesize methane, ethane and ethyne
2. To characterize the prepared methane, ethane and ethyne
INTRODUCTION
Saturated Aliphatic Hydrocarbon
Alkane
Methane is first member of the family of hydrocarbons. It can be prepared in the laboratory by the reduction of any halogenated derivatives of alkane. This type of reaction involves the replacement of one or more atoms of halogen . The generalized scheme is:
RX HX
The chemical properties of methane are characteristic of the alkanes as groups. A convenient test for alkanes which distinguishes them from unsaturated aliphatic hydrocarbons consist of treatment with bromine in carbon tetrachloride. If it is an alkane; almost no reaction occurs in the dark. In bright artificial light or in sunlight, the bromine colour is gradually discharged as the substitution reaction proceeds and hydrogen bromide (HBr) is evolved.
To test for HBr, blow you breath gently across the mouth of the reaction tube. HBr, if present, will dissolve in the moisture of your breath to form a cloud of droplets.
Unsaturated Aliphatic Hydrocarbons
Unsaturated aliphatic hydrocarbons have one or more multiple (double or triple) carbon-carbon bonds per molecule.
Alkenes
The distinguishing feature of the alkene hydrocarbons is the carbon-carbon double bond. The synthesis of alkene can be accomplished by elimination of atoms or groups from two adjacent carbon atoms. The production of 2- methyl -2- butane from t amyl alcohol is an example of the acid catalysed dehydration of alcohols.
Two tests can be carried for an alkene i.e:
a. Bromine, dissolved in carbon tetrachloride , adds rapidly to alkenes at room temperature to form dibromides
Evidence for the reaction is the disappearance of the bromine colour, even in the dark with no evolution of hydrogen bromide
b. Baeyer Test. Alkenes react with neutral permanganate solution to form glycols.
AlkynesThe distinguishing features of an alkynes is a carbon-carbon triple bond. Alkynes give positive Baeyer Test for unsaturation with aqueous potassium permanganate.
This experiment contains two parts: In Part A, you will synthesize methane, ethane and ethyne In Part B, you will characterize prepared methane, ethane and ethyne.
MATERIAL AND METHODS
Materials
Chemicals
10 gZinc dust
60 ml ethanol
5 mlchloroform
1 ml10% copper sulfate solution
1 g Aluminium oxide
3Small pieces of calcium dicarbide
6 mlTetrachloride
12 ml0.3% solution of potassium permanganate
1 mlAcidified potassium permanganate
6 mlAlkaline potassium permanganate
Rocksil wool
MethodsPart A
Preparation of Methane by reduction of chloroform
1. Add 10 g of zinc dust into a 50 ml round bottomed flask mounted in a ring stand
2. Add 10 ml of ethanol and 10 ml of water
3. Fit the flask with a rubber stopper and a delivery tube for collection of the gas over water (see Figure 1.1)
4. Add to the mixture 5 ml of chloroform and 1 ml of 10 % copper sulfate solution.
5. The reaction may require several minutes to start. If it becomes too rapid, cool the flask in a pan of cold water.
6. After the air in the flask has been displaced, collect (over water) at least 6 test tubes of methane by keeping the bottles (or test tubes) inverted over the water.
Figure 1.1 Apparatus for the Synthesis of Methane by the Reduction of Chloroform
Preparation of Ethene
1. Place Rocksil wool at the bottom of test tube. Drop 8 10 drop of ethanol until the rocksil wool has been soaked up with ethanol.
2. Place about 1 g of aluminium oxide halfway along the tube ( see Fgure1.2)
3. Fit a cork and delivery tube to the test tube and heat the aluminium oxide with a gentle flame
4. Collect at least 6 test tubes of ethene by displacement of water.
Figure 1.2: Apparatus for the Synthesis of Ethene
Preparation of Ethyne
1. Place 2 or 3 small pieces of calcium dicarbide in the a test tube (Figure 1.3) and arrange the apparatus for collection of ethyne
2. Add 2 or 3 drops of water at a time.
3. Collect at least 6 test tubes of ethyne by displacement of water
Figure 1.3 Apparatus for the Synthesis of EthynePart BCharacterization Tests for Methane, Ethene and Ethyne1. Prepare FIVE sets of tubes, each set consist of 3 test tubes containing methane, ethene, and ethyne),
2. To set 1A and 1B, add 1 ml of a 4% solution of bromine in carbon tetrachloride. Stopper all the test tube. Place one set of tubes (set 1A) containing methane, ethene and ethyne in your drawer for 15 minutes. Leave the other the other set (set 1B) in bright light (preferably sunlight).After 15 minutes, observe the results. Open the stopper and blow your breath across the mouth of each tube. Note and record any difference.
3. To set 2A, swirl about 2 ml of a 0.3 % solution of potassium permanganate in test tubes containing methane, ethene and ethyne. Record your observations.
4. Set 2B; shake the tubes containing methane, ethene and ethyne with alkaline potassium permanganate solution (made by dissolving about 0.1 g of anhydrous sodium carbonate in 1 cm3 of 1 % potassium permanganate solution). Record your observations.
5. Set 2C; add about 1 cm3 of acidified potassium permanganate (by adding 1 cm3 of sulphuric acid to 0.5 ml of 1% potassium permanganate solution). Record your observations.
RESULT
No TestObservation
Methane
EtheneEthyne
1SET 1A
Tubes left in darkness
2SET 1B
Tubes left in a bright light
3SET 1A & 1B
Blowing across the mouth of each of the test tubes
4SET 2 A
2 ml of 0.3% potassium permanganate solution
5SET 2 B
1 ml Alkaline potassium permanganate
6.
SET 2 C
2 ml Acidified potassium permanganate solution
DISCUSSION
(Hints: Discuss on your findings and relate to your theory and objective of experiment). CONCLUSION(Hints: Conclusion should contain summary of the results, sum up what you have learned from the lab and state whether the objective has been achieved. The conclusion should be one paragraph of 5 7 sentences).POST LABORATORY QUESTIONS
1. What do 'saturated' and 'unsaturated' mean when applied to hydrocarbons? Give
examples of a saturated hydrocarbon and an unsaturated hydrocarbon.2. Give Five (5) sources of methane.3. Describe reactions that are characteristics of alkanes, alkenes and alkynes.
4. Write a balanced equation for the reaction which methane was obtained by the reduction of chloroform.
5. Provide 2 (TWO) other methods of collecting gas that can be used in this experiment.
EXPERIMENT 2
RECRYSTALLIZATION OF BENZOIC ACID
OBJECTIVE
To purify benzoic acid by recrystallization
To determine the melting point of pure benzoic acid
INTRODUCTIONThe products of chemical reactions can be impure. Purification of your products must be performed to remove by-products and impurities. Liquids are customarily purified by distillation, while solids are purified by recrystallization (sometimes called simply "crystallization").
Recrystallization is a method of purifying a solid. There are two types of impurities: those more soluble in a given solvent than the main component and those less soluble. (If there are any impurities that have the same solubility as the main component, then a different solvent needs to be chosen.)
When organic substances are synthesized in the laboratory or isolated from plants, they will obviously contain impurities. Several techniques for purifying these compounds have been developed. The most basic of these techniques for the purification of organic solids is recrystallization, which relies on the different solubilities of solutes in a solvent. Compounds, which are less soluble, will crystallize first. The crystallization process itself helps in the purification because as the crystals form, they select the correct molecules, which fit into the crystal lattice and ignore the wrong molecules. This is of course not a perfect process, but it does increase the purity of the final product.
Organic compounds that are solids at room temperature are usually purified by recrystallization. The general technique involves dissolving the materials to be recrystallized in hot solvent (or solvent mixture) and cooling the solution slowly. The solid that crystallized out from the solution is very pure material.
During the recrystallization process, solid impurities (Such as dust, filter paper etc) that do not dissolve in hot solution are normally eliminated through filtration. The dissolved impurities remain in cold solution while the pure compound recystallize out of the solution . The general procedure for recrystallization is as shown in the flow chart below:
MATERIALS AND METHODS
MATERIALS
ChemicalsApparatus
Benzoic acidConical FlasksFilter funnel
Distilled waterHirsch / Buchner funnelCapillary tubes
Watch glassBeaker
METHODSPART A1. Weight about 1.0 g benzoic acid into a 100 ml conical flask. Add 15 ml water and anti bumping granules (3-5 pieces).
2. Heat the mixture on a hot plate until the solvent boils. Add successive small volumes of water (2-3 ml) [if required] and continue boiling until all benzoic acid has dissolved (apart from insoluble impurities).
3. While waiting for the solution to boil, prepare the fluted filter paper and put it in the funnel. Put the funnel fitted with fluted filter paper in the oven until it is ready to be used.
4. Heat 20ml water in a beaker. Filter the hot mixture of benzoic acid through a fluted filter into conical flask. If the filtration is done in batches, keep the remaining solution hot throughout the filtration process.
5. If crystallization occurs on the filter paper, add a minimum volume of boiling water to redissolve the crystals, and allow the solution to pass through the funnel. Add hot solvent in small volumes until all crystals are dissolved. After filtration, boil the filtrate to produce a more concentrated solution.
6. Cover the conical flask with a watch glass and allow the solution to cool to room temperature, then in an ice-bath after the crystallization has occurred. If no recrystallisation occurs at this stage, it may be due to the fact that too much solvent was used. Concentrate the solution by heating on the hot plate and cool.
7. When all the benzoic filter the crystals through a Hirsch/ buchner funnel by rinsing the flask with some of the filtrate. Wash the crystal with a little cold water and dry. Place the filter paper containing crystals in a watch glass and leave it for at least four (4) hours to air dry. NOTE:
DO NOT FORGET TO TAKE THE WEIGHT OF FILTER PAPER WITH AND WITHOUT BENZOIC ACID.
PART B
1. After the crystal dry completely, weigh the pure benzoic acid recovered, calculate the % recovered
2. Break the crystal into powder, fill the powder in three (3) capillary tubes.
3. Read the melting point using BUCHI B540.
4. Compare the result with the actual melting point of benzoic acid.
RESULTS1. Data on the impure Benzoic Acida) Mass of benzoic acid + Weighing paper:
b)Mass of weighing paper:
c)Mass of impure benzoic acid:
2. Data for recrystallized benzoic acid
a)Mass of recrystallized benzoic acid + Weighing paper:
b)Mass of weighing paper:
c)Mass of recrystallized benzoic acid:
d)Calculation of percentage recovery
(Show calculation )
:
e)Melting point of recrystallized benzoic acid
2. Melting point of recrystallized benzoic acid (Theory) : DISCUSSION
(Hints: Discuss on your findings and relate to your theory and objective of experiment). CONCLUSION(Hints: Conclusion should contain summary of the results, sum up what you have learned from the lab state whether the objective has been achieved. The conclusion should be one paragraph of 5 7 sentences).
POST LABORATORY QUESTIONS
1. What is the purpose of the recrystallisation process?.
2. Explain why anti bumping are added before any solution is heated ?.
3. Why is suction filtration favoured over gravitational filtration when separating pure crystals from its supernatant liquid after the recrystallisation?.
4. In general, water is not a good solvent for the recrystallisation. Explain this statement.
5. Provide the probable reason(s) of low or high melting point of your experimental benzoic acid when compared to theoretical result.
6. List the usages of benzoic acid in industry.7. State the class/family of benzoic acid in organic chemistry. 8. Draw the structure of benzoic acid. 9. How is benzoic acid been synthesized?.
a. Write the chemical equation of above process.b. Name the starting material, process name, catalyst being used and side product. EXPERIMENT 3
CONVERSION OF ETHYL ALCOHOL TO ETHYL ACETATE
OBJECTIVE
To convert ethanol to ethyl acetate (ethyl ethanoate)
INTRODUCTIONChemist use organic synthesis both to make larger amounts of useful natural compounds and to invent totally new compounds in search of improved properties and biological effects. This experiment provides a synthesis step to convert raw material such ethanol to ethyl acetate. Reaction involved is called esterification.
Carboxylic acid alcohol ester water
The reaction of a carboxylic acid with an alcohol to produce an ester plus water is known as the Fisher esterification reaction. A mineral acid, usually sulfuric acid is used as a cataly
MATERIALS AND METHODS
CHEMICALAPPARATUS
EthanolRound bottom flask
Glacial acetic acidWater / Liebig condenser
Conc. Sulfuric acidRetort stand
30% sodium carbonate solutionseparating funnel
calcium chloride
granular anhydrous calcium chloride
anti bumping granules
METHODS8. Mix 50 ml of 95% ethanol and 50 ml of glacial acetic acid thoroughly in a 250 ml round bottomed flask.
9. Add slowly with cooling and shaking of 10 ml of concentrated H2SO4.
10. Ensure that the mixture is homogenous, then fit the flask with a reflux water condenser (as in figure 4.1) and boil the mixture gently for 10 minutes. Cool the flask and its content. If the flask and its content are not cooled sufficiently, there will be some loss of material by evaporation.
Figure 4.1a: Reflux set up
Figure 4.1b: Reflux set up
11. Rearrange the position of the condenser for distillation (see figure 4.2) and put a few boiling chips in the flask. A filter flask, whose side arm is joined to a rubber tube leading over the edge of laboratory bench, is used as a receiver. Ethyl acetate is highly flammable. Therefore any vapors should be conducted off the table towards the floor. Distlled off about 2/3 of the mixture.
Figure 4.2a: Distillation set up
Figure 4.2b: Distillation set up.
12. Transfer the distillate to a separating funnel (figure 4.3) and add about 25 ml of 30 % Na2CO3 solution. Stopper the funnel, invert it and shake it, opening the stopcock from time to time.
Figure 4.3a Separating funnel set-up.
Figure 4.3b Method to invert and shake the separating funnel
13. Allow the two layers to separate. Carefully run off and reject the lower layer, ensuring that the sodium carbonate is removed as completely as possible. 14. Prepare a solution of 25 g of calcium chloride in 25 ml of water. Add if to crude ethyl acetate in the funnel. Shake vigorously. Allow the mixture to separate. Run off the lower aqueos as completely as possible.15. Run the ethyl acetate into a small conical flask. Add a few lumps of granular anhydrous calcium chloride. Shake occasionally until the liquid is clear.
16. Decant the liquid some anti bumping granules. Arrange for distillation (with a 0 100 oC thermometer in the apparatus). Pre weight the receiving flask. The distilling flask should be placed in cold water bath, which is gradually heated.
17. The ether that is always formed in this reaction will distill off at 35 45 oC and may be discarded. Continue to heat and collect the fraction that boils between 74 oC and 79 oC.
18. Weight your product and calculate the percentage yield.RESULTS
Volume of ethanol:ml
Weight of ethanol:g
Volume of acetic acid:ml
Weight of acetic acid:g
Theoretical yield:g
Weight of receiving flask.g
Weight of Product
+
Receiving flaskg
Weight of ethyl ethanoate
(Actual yield):g
Percentage yield:%
Show all calculations, otherwise will be NO MARKS.DISCUSSION
(Hints: Discuss on your findings and relate to your theory and objective of experiment). CONCLUSION(Hints: Conclusion should contain summary of the results, sum up what you have learned from the lab state whether the objective has been achieved. The conclusion should be one paragraph of 5 7 sentences).
POST LABORATORY QUESTIONS 1. a) Write and balance the equation for the reaction of acetic acid with ethanol to produce ethyl ethanoate and water.b) In the reaction of above example, how many grams of ethyl ethanoate would be produced if 50 ml of ethanol were react with 50 ml acetic acid? Which is the limiting reagent? (given (ethanol: 0.8 g/ml and (acetic acid : 1.06 g/ml and (ethyl acetate: 0.9g/ml). c) Calculate the percentage yield if 50.0 g of ethyl ethanoate was obtained from the experiment. 2. What is the function of reflux water condenser?.3. Why must the concentrated sulphuric acid be added slowly and with cooling?
4. What is the function of sodium carbonate solution and anhydrous calcium chloride?
5. Explain the phenomena of 2 layers formed in the separating funnel. EXPERIMENT 4
SAPONIFICATION REACTION OF FAT: SOAP PRODUCTION
OBJECTIVE
To synthesize a sample of hard soap
To test the soap produced.
INTRODUCTIONThe procedure of making soap involves the basic hydrolysis (saponification) of a fat. Chemically, fats are referred to as triglycerides. They contain ester functional groups. Saponification involves heating fat with an alkaline solution. The alkaline solution hydrolyzes the fat to alcohol and the salt of a long chain carboxylic acid (soap).When common salt is added, the soap precipitates. The soap is washed free of unreacted alkaline solution and molded into bars.
This experiment contains two parts: In Part A, you will synthesize Soap In Part B, you will test prepared soap.
MATERIALS AND METHODS
MATERIALSCHEMICALS
APPARATUS
NaOHConical Flasks
95% ethanolBeaker
FatFilter funnel
50% water/ethanol mixture NaCI SolutionHirsch / Buchner funnel
4 % calcium shloride solutionWatch glass
Trisodium phospahteMeasuring cylinder
METHODSPart A
Preparation of Soap
19. Prepare a NaOH solution (about 0.25 g sodium hydroxide dissolved in a mixture of 1.0 ml of distilled water and 1.0 ml of 95% ethanol)..
20. Place about 0.25 g of fat in a 50 ml conical flask and add the prepared sodium hydroxide solution to the flask.
21. Heat the mixture in a in a bath of 100 oC.
22. Cover the flask with some aluminium foil to help reduce evaporation. Swirl the Erlenmeyer flask every few minutes. Use tong to do this.
23. The soap will precipitate from the boiling mixture within 20 minutes.
24. If you observe that some alcohol and water is evaporating from the flask, you may add up to 0.4 ml of a 50 % water/alcohol mixture to replace the solvent.
25. Heat the mixture for a maximum time of 25 minutes.
26. Place 4 ml of NaCI solution in a 15 ml beaker and transfer the saponified mixture from flask to beaker.
27. Stir the mixture while cooling the beaker in an ice-water bath.
28. Collect the prepared soap on a Hirsch funnel of ice cold distilled water to remove excess NaOH.
29. Continue to draw air through the filter for a few minutes to partially dry the product. Test your soap with the procedure below.
Part B
Testing on prepared Soap
1. Remove about 0.01 g of soap from the filter paper and placed it in a clean 10 ml graduated cylinder
2. Add 3 ml of distilled water, close the cylinder with your thumb and shake the mixture vigorously for about 15 sec.
3. After about 30 sec standing, note down the level of the foam.
4. Check the pH of the aqueous solution.
5. Add 5 10 drops of 4% calcium chloride solution to the soap mixture from a Pasteur pipette .Shake the mixture for 15 sec and allow it to stand for 30 seconds. Observe the effect of addition the calcium chloride.
6. Then add 0.5 g of trisodium phosphate and shake the mixture again for 15 seconds. After 30 sec. again observe the result.
RESULTSConditionsObservation
1. Soap + 3 ml distilled water:
2.Test with litmus paper:
3.Mixture from No 1 + 5-10 drops of 4% calcium chloride:
4.Mixture from No 2 + 0.5 g trisodium phosphate:
DISCUSSION
(Hints: Discuss on your findings and relate to your theory and objective of experiment) CONCLUSION(Hints: Conclusion should contain summary of the results, sum up what you have learned from the lab state whether the objective has been achieved. The conclusion should be one paragraph of 5 7 sentences).
POST LABORATORY QUESTIONS
1. Give a definition of saponification.2. Explain how soap can function as dirt remover.
3. Synthetic detergent functions in the same way as soaps. Give the advantages of synthetic detergent over soaps.4. Reaction of fat with NaOH will produced long chain carboxylic acid (soap) in form of Bar. What would be happen if sodium Hydroxide (NaOH) is replaced by Potassium hydroxide (KOH) .5. Name the all types of chemical reaction in this experiment. 6. Explain the reason of your findings for the followings:
a. Soap + 3 ml distilled wter.b. Soap mixture + 5-10 drops of 4% calcium chloride.c. Soap mixture + 0.5 g trisodium phosphate.
reduction
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Dark Brown Precipitate
Purple
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3 NaOH
+
+
glycerol
Sodium salt of an acid (soap)
Fat
1
_1262400947.cdx
_1265225221.cdx
_1265225943.cdx
_1265225739.cdx
_1262401102.cdx
_1262372636.cdx
