APPLIED MICROBIOLOGY &

BASIC

CHEMISTRY SCBT 31111PRACTICAL MANUAL

GENERAL LABORATORY SAFETY PROCEDURESBasic PrecautionsAwareness is the most fundamental rule of chemical safety. Take time to understand the safety and health hazards of the chemicals in the workplace. Every laboratory worker should take the following precautions:

1. Clothing: When handling dangerous substances, wear gloves, laboratory coats, and safety shield or glasses. Shorts and sandals should not be worn in the lab at any time.

2. Close shoes are required when working in the labs.

3. If you have long hair or loose clothes, make sure it is tied back or confined. 4. Wear gloves when using any hazardous or toxic agent.

5. Review the safety and health hazard data of all chemicals used in the laboratory.

6. Know the signs and symptoms of overexposure and the physical and sensory characteristics (odor, appearance) of these chemicals.

7. Know appropriate procedures for emergencies, including the location and operation of all emergency equipment.

8. Avoid distracting or startling others.

9. Avoid leaving experiments unattended.

10. Never use unlabeled chemicals or chemicals.

11. Always order the least amount of chemical required.

12. Use appropriate personal protective equipment at all times.

13. Use hazardous chemicals in a chemical fume hood, whenever possible.

14. Use guards and shields where possible. All mechanical equipment should have adequate guarding.

15. Use safety shields when there is a possibility for explosion or implosion.

16. Store and handle chemicals in accordance with the guidelines. Treat every chemical as if it were hazardous.

17. Make sure all chemicals are clearly and currently labeled with the substance name, concentration, date, and name of the individual responsible.

18. Never return chemicals to reagent bottles. (Try for the correct amount and share any excess.)

19. Dispose of hazardous waste through the University Hazardous Waste Program.

20. Avoid pouring chemical waste materials into the sink.

21. Do not eat, drink and smoke,

22. Do not store food or beverages in the laboratory or in a chemical refrigerator.

23. Report all accidents, even if they do not result in injury, to the Scientific Officer /Lab Manager immediately.

LEARNING OUTCOMESYou will be evaluated on the following Programme Learning Outcomes (PO) :Programme Learning Outcomes

PO1Ability to demonstrate a comprehensive understanding of Biotechnology

PO2Ability to operate and maintain basic Biotechnology equipment

PO4Ability to analyse, synthesise and integrate knowledge and information

This PO will be commented but NOT evaluated :

Programme Learning Outcomes

PO3Ability to communicate and demonstrate interpersonal skills

ASSESSMENT CRITERIAPO1 : Ability to demonstrate a comprehensive understanding of Biotechnology This is to evaluate students on the knowledge aspect of the practical work. It will be based on the submitted written report of a particular laboratory practical.MarksDescriptors

PO1

60The student does not reach a standard described by any of the descriptors given below

1-2The student recalls some scientific ideas and concepts and applies these to solve simple problems

3-4The student explains scientific ideas and concepts and applies scientific understanding to solve problems in familiar situations. The student analyses scientific information by identifying parts, relationships or causes. The student provides an explanation that shows understanding.

5-6The student explains scientific ideas and concepts and applies scientific understanding to solve problems in familiar and unfamiliar situations. The student analyses and evaluates scientific information by making scientifically supported judgments about the information, the validity of the ideas or the quality of the work.

PO2 : Ability to operate and maintain basic Biotechnology equipmentThis is to evaluate students on the practical skills. It will be based on the performance of students during the practical session.MarksDescriptors

PO2

60The student does not reach a standard described by any of the descriptors given below

1-2The student requires guidance and supervision when using laboratory equipment. The student can work safely and cooperate with others but may need reminders.

3-4The student uses most equipment competently but might require occasional guidance; on most occasions pay attention to safety and works responsibly with the living and non-living environment. The student generally cooperates well with other students

5-6The student works largely independently; uses equipment with precision and skill; pays close attention to safety and deals responsibly with the living and non-living environment. The student consistently works effectively as part of a team, collaborating with others and respecting their views.

PO4 - Ability to analyse, synthesise and integrate knowledge and informationThis is to evaluate students on the data analysis, results presentation, discussion and conclusion. It will be based on the submitted written report of a particular laboratory practical.MarksDescriptors

PO4

60The student does not reach a standard described by any of the descriptors given below.

1-2The student organizes and presents data using simple numerical or diagrammatic forms and draws an obvious conclusion.

3-4The student organizes and transforms data into numerical and diagrammatic forms and presents it using appropriate communication modes. The student draws a conclusion consistent with the data.

5-6The student organizes and transforms data into numerical and diagrammatic forms and presents it logically and clearly, using appropriate communication modes. The student explains trends, patterns or relationships in the data, comments on the reliability of the data, draws a clear conclusion based on the correct interpretation of the data, and explains it using scientific reasoning.

PO3 - Communicate and demonstrate interpersonal skillsThis is to evaluate students on the presentation of the lab reports such as format, spelling, etc. It will be based on the submitted written report of a particular laboratory practical.LevelsDescriptors

PO3

Level 0The student does not reach a standard described by any of the descriptors given below.

Level 1The student attempts to communicate scientific information using some scientific language. The student presents some of the information in an appropriate form using some symbolic or visual representation when appropriate. The student attempts to acknowledge sources of information but this is inaccurate.

Level 2The student communicates scientific information using scientific language. The student presents most of the information appropriately using symbolic and / or visual representation according to the task. The student acknowledges sources of information with occasional errors.

Level 3The student communicates scientific information effectively using scientific language correctly. The student presents all the information appropriately using symbolic and / or visual representation accurately according to the task. The student acknowledges sources of information appropriately.

PRACTICAL 1: THE SCIENCE OF SOAP AND DETERGENTObjectiveTo make soap and detergentTo differentiate soap and detergent

Introduction

A soap is a salt of a compound known as a fatty acid. A soap molecule consists of a long hydrocarbon chain (composed of carbons and hydrogens) with a carboxylic acid group on one end which is ionic bonded to a metal ion, usually a sodium or potassium. The hydrocarbon end is nonpolar and is soluble in nonpolar substances (such as fats and oils), and the ionic end (the salt of a carboxylic acid) is soluble in water. The structure of a soap molecule is represented below:

O

||

CH3-CH2-CH2- CH2-CH2-CH2-CH2- CH2-CH2- CH2-CH2- CH2-CH2- CH2-CH2- C-O Na+

Non-polar hydrocarbon chain ionic end (soluble in nonpolar substances) (soluble in water) Detergents are structurally similar to soaps, but differ in the water-soluble portion. Three examples of detergents are shown below.

When a soap or detergent is added to water, a polar solvent, the molecules form clusters, known as micelles, in which the polar ends of the molecules are on the outside of the cluster and the non-polar ends are in the middle (See Figure 1).The cleaning action of both soaps and detergents results from their ability to emulsify or disperse water-insoluble materials (dirt, oil, grease, etc.) and hold them in suspension in water. This ability comes from the molecular structure of soaps and detergents. When a soap or detergent is added to water that contains oil or other water-insoluble materials, the soap or detergent molecules surround the oil droplets. The oil or grease is dissolved in the alkyl groups of the soap molecules while the ionic end allows the micelle to dissolve in water. As a result, the oil droplets are dispersed throughout the water (this is referred to as emulsification ) and can be rinsed away.

Soaps, will react with metal ions in the water and can form insoluble precipitates. The precipitates can be seen in the soapy water and are referred to as soap scum. This soap scum can form deposits on clothes causing them to be gray or yellow in color. To eliminate the metal ions in water, washing aids such as washing soda (sodium carbonate) and borax (sodium tetraborate) were added to the wash water. These compounds would precipitate the metal ions, eliminating most of the soap scum. With the discovery of synthetic detergents, much of the need for washing aids was reduced. A detergent works similar to a soap, but does not form precipitates with metal ions, reducing the discoloration of clothes due to the precipitated soap. Modern laundry detergents are mixtures of detergent, water softeners, optical brighteners, stain removers, and enzymes.

Safety Precautions

Wear goggles or safety glasses at all times in the laboratory.Sodium hydroxide is caustic. Avoid skin contact. In the event of contact with your skin, was the affected areas well with water until your skin no longer feels soapy. If redness occurs, consult qualified medical assistance.Ethanol is flammable. Keep the container covered and take care to avoid flames.Sulfuric acid is extremely corrosive and can cause severe burns. In the event of skin contact, immediately rinse the affected area with water. If any gets on your clothes, remove the affected item of clothing and wash both the clothing and the area of suspected skin contact. If skin is blistered or broken, consult qualified medical assistance.

Experimental Procedure

A. Preparation of a soapPrincipleSoaps are prepared by the alkaline hydrolysis of fats and oils. This process is known as saponification.

A by-product of this reaction is glycerol which is useful as in foods, as an antifreeze, as a tobacco-moistening agent, and in the manufacture of nitroglycerine and dynamite.Materials/ ApparatusLard

Sodium hydroxide, NaOH, pellets

Sodium chloride, NaCl, technical grade

Ethanol, C2H5OH, 95%

Boiling chips

Erlenmeyer flask, 125-mL

Beakers, 2 400-mL, 150-mL

Graduated cylinders, 25-mL, 125 or 250-mL

Funnel

Spatula

Stirring rod

Cheesecloth

Ring stand

Clamp to hold Erlenmeyer flask

Watch glass

Procedure1) Weigh 5 g of solid sodium hydroxide, NaOH, into a clean 100 or 150-mL beaker. Add 15 ml of ethanol, and 15 ml of distilled water to the beaker. Stir to dissolve the sodium hydroxide.2) Place about 5 g of lard or shortening into a 125 mL Erlenmeyer flask..3) Add the solution of sodium hydroxide to the lard or shortening in the flask.4) Add 2 or 3 boiling chips to the flask, and cover it with a watch glass.5) Arrange the apparatus as shown in Figure 2. If a hot plate is used, support the flask over a beaker of water placed on the hotplate surface.6) Heat the flask in the steam just above the water surface of a boiling water bath. As the water in the bath evaporates, lower the reaction flask so the bottom almost makes contact with the boiling water surface.7) Remember to temporarily remove the watch glass while you make this adjustment so that it does not fall and break.8) Allow the reaction to proceed for at least 30 minutes.9) While saponification proceeds, prepare a salt solution by dissolving about 25 g of sodium chloride, NaC1, in 150 ml of water contained in a 400 ml beaker.

10) NOTE: If you are preparing a detergent (Part B of this experiment), start that preparation now.

11) Prepare a mixture of about 25 mL of ice water.

12) After 40 minutes turn off your burner or the hotplate, remove the flask from the heat (you can use the clamp securing the flask as a handle) and pour the hot reaction mixture into the salt solution.

13) Pour a small amount of the mixture from the beaker back into the reaction flask to rinse out most of the remaining reaction mixture. Add the rinse material to the beaker.

14) Stir the resulting mixture in the beaker thoroughly for several minutes.

15) Filter the mixture through a funnel containing 2 or 3 layers of cheesecloth.

16) Wash the collected soap twice with l0 mL portions of ice-cold water.

17) Remove the cheesecloth from the funnel, and twist it to remove excess water from the soap. Save the soap for Part C of the experiment.

Figure 2. Apparatus for the preparation of the soap.

B. Preparation of a Detergent Principle

A synthetic detergent, a sodium alkyl sulfate called sodium dodecylsulfate, will be prepared by reacting dodecyl alcohol (dodecanol) with sulfuric acid.

dodecanol sulfuric acid dodecylsulfateThe resulting dodecylsulfate is converted to the sodium salt by a reaction with sodium hydroxide.

dodecylsulfate sodium dodecylsulfateMaterials/ Apparatus

Dodecanol (dodecyl alcohol), C12H25OH

Sulfuric acid, H2SO4, concentrated

Sodium hydroxide, NaOH, 6M

Phenolphthalein solution, 1%

Sodium chloride, NaCl, technical grade

Erlenmeyer flask, 125-mL

Beakers, 400-mL, 150-mL, 100-mL

Graduated cylinders, 10-mL, 25-mL, 125-mL

Funnel

Spatula

Stirring rod

Cheesecloth

Watch glassScissors

Procedure

1) Place 5 ml of dodecanol into a 100-mL beaker.2) Measure 2 mL of concentrated sulfuric acid, H2SO4, in a 10-mL graduated cylinder.

With stirring, slowly add the 2 mL of concentrated sulfuric acid to the dodecanol in the beaker. Continue to stir for 1 minute after addition of the sulfuric acid is complete. Let the mixture stand for 10 minutes.

3) Fill a 250-mL beaker one-third full of ice, add about 10 g of sodium chloride, NaCl, and mix thoroughly.

4) Add water to bring the total volume of the mixture to 75 ml.

5) Mix 5 ml of 6 M sodium hydroxide with 10 mL of water in a small beaker. Mix well, then add 4 drops of phenolphthalein indicator. The pink color of the phenolphthalein may begin to fade in the strongly basic solution.

6) Prepare a mixture of about 25 mL of ice water.

7) After the 10 minutes, carefully pour the sodium hydroxide solution into the dodecanol-sulfuric acid mixture. Stir until the pink color disappears. A large amount of solid detergent should form.

8) Pour the detergent mixture into the ice-salt bath. Stir to break up large lumps of detergent.

9) Filter the precipitated detergent mixture through 2-3 layers of cheesecloth in a funnel mounted on a ringstand.

10) Wash the collected detergent twice with 10 ml portions of ice-cold water.

11) Remove the cheesecloth from the funnel, squeeze excess water from the solid detergent, and save the detergent for use in Part C.C. Properties of soap and detergentSoaps and detergents are similar in their general structure and properties, but different in their composition and some specific properties. This will become apparent to you as you study the following characteristics: emulsifying properties, behavior in hard water, alkalinity, and ability to react with mineral acids.

In each of the following tests use the soap and detergent you prepared in parts A and B of this experiment. If you were unsuccessful in preparing the soap or the detergent, you can use a sample of Ivory soap and/or laundry or dishwashing detergent available in the laboratory.A. Preparation of Testing Solutions1) Prepare a soap solution by dissolving about 1 g of your laboratory made soap in 60 mL (4 tablespoons) of warm water. (Distilled water is preferred, but not essential) (If desired, you can prepare solutions of your lab soap and a household soap.)

2) Prepare a detergent solution by dissolving about 1 g your laboratory made detergent in 60 mL (4 tablespoons) of warm water. . (Distilled water is preferred, but not essential) (If desired, you can prepare solutions of your lab detergent and a household detergent.)

3) Dip a clean glass stirring rod into each solution, the soap and the detergent. How does the residue on the stirring rods compare?

NOTE: Save these solutions. They will be used in all remaining parts of this experiment.

B. Emulsifying Properties

As a result of their molecular structures, soaps and detergents are both capable of emulsifying or dispersing oils and similar water-insoluble substances.1) Place 4 drops of an oil (either mineral oil, cooking oil, or household lubricating oil) into each of three separate test tubes.

2. Add 5 mL of water to one tube, 5 mL of soap solution to another, and 5 mL of detergent solution to the third. Stopper and shake each tube vigorously for 30 seconds to one minute.

3) Observe the degree of oil emulsification in each tube as indicated by the presence of suds and the absence of oil droplets in the liquid, or the absence of oil scum on the inside of the test tube.

4) Record your results.C. Behavior in Hard Water

The sodium and potassium salts of most carboxylic acids are water soluble. However, the calcium, magnesium, and iron salts are not. Thus, when soaps are placed in hard water that contains such ions, an insoluble, curdy solid forms. Most of us have seen these results in the form of a bathtub ring or soap scum floating in bath or wash water. This process removes soap ions from solution, and decreases the cleaning effectiveness of soaps.

a soluble soap an insoluble soapThe calcium, magnesium, and iron forms of most detergents are more soluble in water than the corresponding soap compounds. Consequently, detergents function almost as well in hard water as they do in soft water.1) Place 5 mL of soap solution in each of three test tubes.

2) Place 5 mL of detergent solution in each of three test tubes.

3) Add 2 mL of 1% calcium chloride, CaCl2, to one soap-containing tube and one detergent-containing tube. Repeat this process, using 1% magnesium chloride, MgCl2, and 1% iron(III) chloride, FeCl3, solutions.

4) Mix the contents by stoppering and inverting each tube several times. (Do NOT shake vigorously.) Note whether or not a precipitate forms and how much of a precipitate (very large, large, little, or none).

5. Add 4 drops of oil (mineral oil, cooking oil, or household oil) to each tube, stopper, and shake the mixture vigorously.

7. Observe and record the emulsifying ability of the soap or detergent in each tube as indicated primarily by the amount of suds formed. (heavy suds, light suds, few, or no suds).

D. Alkalinity

Soaps undergo a hydrolysis reaction in water. As a result, soap solutions tend to be alkaline. Detergent solutions, on the other hand, are more neutral.1) Test small samples of your soap and detergent solutions with red litmus paper. If alkaline, the red litmus paper turns blue.

2. Test small samples (20 drops) of your soap and detergent solutions by adding 2-3 drops of phenolphthalein indicator. Phenolphthalein is pink at a pH of 8 or higher (alkaline solutions).

3) Record your results.E. Reaction with Mineral Acid

Soaps, the sodium salts of fatty acids, are water soluble, but the fatty acids themselves are not. A soap can be converted into the fatty acid by means of a reaction with a strong mineral (non-organic) acid.

Thus, the acidification of a soap solution causes the fatty acid to precipitate. Acidification of detergents, on the other hand, produces acids which are often water soluble.1) Place 5 mL of soap solution into a test tube.

2) Add dilute (1M) hydrochloric acid dropwise until the well-mixed test tube contents turn blue litmus paper red.

3) If the solution is warm or hot, cool the mixture in an ice bath for 3-4 minutes with occasional stirring.

4) Note and record the formation of any precipitate.

5) Repeat steps 1, 2 and 3, using your detergent solution. (NOTE: The solution may turn blue litmus to red without adding any HCl. If that occurs, add the same number of drops of HCl that you used with the soap solution in step 2, above. Note and record whether a precipitate is present.

References1.Katz, D.A. (2007). The science of soaps and detergents.Report format: The science of soap and detegent*Report need to be submitted one week after the practical.

Questions:PO4 - Ability to analyse, synthesise and integrate knowledge and information

1) Compare the appearance of the soap and detergent. Do they appear to be the similar or different?

2) How do the properties of the soap and detergent compare when preparing the 1% solutions? Does one dissolve better that the other? How do the solutions compare?

3) Summarize your results of the emulsification tests using the cooking or mineral oil.

4) Summarize your results of the hard water tests. Which substance performs better in hard water, the soap or the detergent? Explain.

5) Do you observe and difference in the alkalinity of the soap and the detergent? Explain.6) Is there any difference in your results with the red litmus paper as compared to the phenolphthalein indicator?7) Summarize the effects of mineral acid on the soap and on the detergent.8) Summarize the results of the soap versus the detergent. Does one perform better than the other?

PO1 : Ability to demonstrate a comprehensive understanding of Biotechnology1) Which is the better emulsifying agent, the soap or the detergent? Explain.2) Is the soap or detergent affected more by one mineral ion (Ca2+, Mg2+, or Fe3+) than the others?PRACTICAL 2: REACTIONS OF COMMON REAGENTS WITH EVERDAY MATERIALSObjectives

To investigate the effects of strong acids, strong bases, and acetone on various materials.IntroductionThis lab has a two- fold purpose. You will discover the kinds of reactions that different chemicals can have on everyday materials and also see what effects milder versions of these chemicals can have on our environment. Acid rain is much more dilute an acid than the concentrated acids that you will be investigating, but the reactions are often the same, just not as quickly.Behavior of Strong Acids

Acids are well known to be corrosive substances. The potential hazard of a given acid depends on a number of factors including the strength and the concentration of the acid. Acids are most readily defined as proton (H+) donors or electron pair acceptors. The ease with which an acid donates a proton determines its strength. Strong acids are extremely reactive and readily lose a proton (H+) or gain an electron pair. Common examples of strong acids that you will investigate today are nitric acid (HNO3), sulfuric acid (H2SO4), and hydrochloric acid (HCl). The vast majority of acids are weak and do not readily lose H+ or gain electron pairs. Weak acids are commonly used in cooking. For example, vinegar is a 5% (by volume) solution of the weak acid, acetic acid (HC2H3O2), while citric acid is the weak acid that gives the tangy taste to lemons.

Acids are usually used as solutions in water and the acid concentration is described using the term molarity (M). This description can be a bit confusing, however, because strong acids of the same molarity are much more reactive than weak acids of the identical molarity and therefore have greater corrosive effects.

Today you will be working with various concentrations of three different strong acids, hydrochloric acid, nitric acid, and sulfuric acid. Nitric and sulfuric acids are examples of oxoacids because they contain oxygen and they have the ability to act as oxidizing agents when concentrated. For this reason they are described as oxidizing acids, whereas hydrochloric acid is a non-oxidizing acid. In addition, concentrated sulfuric acid can also act as a dehydrating agent. This means that it has a high affinity for

water and will even "grab" it out of a molecule such as sugar (C12H22O11).

How to Work Safely with Acids

Because acids are corrosive to skin and clothing, it is most important that they be handled with care and kept off of the skin! If an acid does get on your skin or clothing, immediately flush the area with plenty of water and report the incident to your instructor.

Note, however, that when an acid is added to a base or to water, the reaction will generate heat take precautions. If acid spills on your lab bench, neutralize it with the sodium bicarbonate (NaHCO3(s)) provided. Household baking soda is sodium bicarbonate.

Properties of Strong Bases

In a sense, bases are the opposite of acids: they are proton acceptors or electron pair donors. Strong bases do this readily and are very corrosive, while weak bases are much less reactive. Many students think of a base only as something that contains an OH- group. This is not necessarily the case, however, since lithium hydride (LiH) and ammonia (NH3) are both bases. Common strong bases include sodium hydroxide (NaOH), potassium hydroxide (KOH), and barium hydroxide (Ba(OH)2); most bases are

however weak. Common examples of weak bases include ammonia (NH3), which is the base present in dilute solution in household ammonia, and sodium bicarbonate (NaHCO3, baking soda).

Like acids, the concentration of a base is measured in molarity (M) or, less often, in weight/weight percentage (% w/w). Once again a strong base of a given molarity is much more reactive than a weak base of the same molarity.

Precautions in Handling Bases

In this experiment you will investigate the effect of various concentrations of the strong base sodium hydroxide (NaOH) also known as lye (an active ingredient in Draino). Because bases are corrosive to clothing and the skin, take the same precautions with them as you would with acids: Handle them with care and keep them off your skin! If you splatter a base on your skin or clothing, flush the area with lots of water and report the incident to your instructor. Furthermore, the addition of a base to an acid or

to water generates heat - take precautions. If a base spills on your lab bench, neutralize it with dilute acetic acid solution.

Acetone: An Excellent Solvent

Acetone is a familiar sight in most organic chemistry laboratories. It has the structure shown below, and is neither an acid nor a base. It is highly flammable and must be kept away from heat and open flames. In addition, if it comes in contact with plastic or synthetic fabrics, it may damage or destroy them. Finally, when using acetone to clean glassware, do not breathe in more of the vapors than is necessary. This does not mean you should not breathe while cleaning your beakers - just don't gulp air like a fish

out of water!

Oxidizing and Reducing Agents

Strong oxidizing agents and strong reducing agents are also chemicals that warrant respect. An oxidizing agent is a substance that oxidizes something else; it is itself reduced. Likewise a reducing agent reduces something else; it is itself oxidized in the reaction. Reactions involving oxidation and reduction are termed oxidation-reduction (redox) reactions. You will be learning more about what these terms mean in terms of electron transfer next week. In this laboratory we will experiment with household bleach (Clorox), which is a potent oxidizing agent; household bleach is a dilute solution of

sodium hypochlorite, NaOCl. As mentioned above, nitric acid and sulfuric acid are oxidizing acids; thus part of their reactivity is due to their ability to oxidize other substances.

Materials/ Apparatus 12.5 M NaOH (concentrated) 6 M NaOH (dilute) 16 M HNO3 (concentrated) 6 M HNO3 (dilute) 12 M HCl (concentrated) 6 M HCl (dilute) 18 M H2SO4 (concentrated) 6 M H2SO4 (dilute) 0.6 M H2SO4 (very dilute) Clorox(strong oxidizing agent) Clorox(5.25% NaOCl) Acetone Polystyrene Hair Sugar Egg White Your skin Paper clip Aluminium foilProceduresHair

Hair is made up of melanin, a pigment, and proteins that are linked by hydrogen bonds and sulfur bridges. This investigation will test the ability of a strong base, a strong acid, and a strong oxidizing agent (CloroxTM) to react with the proteins in hair.

1. Obtain four small piles of hair of the same type and place them on separate large (4 inch) watch glasses. Describe the type of hair used here.

2. To each of the hair samples add a sufficient quantity of one of the reagents below so that some of the hair is immersed in the reagent. Allow the hair to react during the duration of your lab.

3. Record your observations towards the end of your laboratory period. Describe any color or structural changes in the hair.

(a) tap water (the control)

(b) 6 M NaOH (dilute)

(c) 16 M HNO3 (concentrated)

(d) Clorox(5.25% NaOCl)Reactions with Clothing

1. Obtain a piece of each kind of clothing (cotton, polyester, nylon) and place them on separate large (4 inch) watch glasses.

2. To each of the clothing samples add a couple drops of each of the reagents below onto different parts of the cloth.

(a) 12 M HCl (concentrated)

(b) 18 M H2SO4 (concentrated)

(c) 12.5 M NaOH (concentrated)

(d) Clorox(strong oxidizing agent)

If no change is evident after 5 minutes, try poking the area with a stirring rod. If there is still no change, rinse the fabric with tap water and dry with a hair dryer. Then poke the area again with a stirring rod: now are there any changes?Polystyrene and Acetone

Polystyrene, also known as styrofoam, is used in molded and plastic items as an insulator (it keeps your coffee and fast food hot). In this portion of the lab, you will examine what happens when polystyrene peanuts and acetone come together; these peanuts are commonly used as packing material when shipping delicate items.

An environmental concern is that polystyrene is non-biodegradable. Recently "environmentally friendly" peanuts have been developed which are made of starch. In this experiment you will test both forms of packing material.

1. Fill a beaker with styrofoam shipping "peanuts" and dribble acetone over them. Remove the liquid "product" and place it on a watch glass to dry. Test the Styrofoam peanuts in the same way with water.

2. Repeat the experiment with the starch peanuts (if available). Record your observations and summarize the differences in reactivity of the two types of packing material.

Biological Materials

1. Sugar. Table sugar (sucrose) is a simple carbohydrate with the molecular formula, C12H22O11. Transfer a small amount of sugar (about a half-teaspoon) to the bottom of a 100 mL beaker. Carefully place ONE drop of concentrated (18 M) H2SO4 on the sugar.

2. Egg White. Egg white (egg albumin) is mostly protein and so can serve as a model for your skin. Place a small blob of egg white on a watch glass and investigate the effect of 6 M HNO3 (nitric acid) on the egg white. Repeat the experiment us ing 6 M NaOH (sodium hydroxide) in place of the nitric acid. Repeat again using Cloroxas the reagent to be tested on the egg white.

3. Skin. Dip your fingers into the very dilute (0.01 M) sodium hydroxide solution provided by the instructor. Rub your fingers together and report how it feels. Rinse your hands immediately with plenty of cold water.Marble

1. To small marble chips add the following while noting differences in reactions and rates of reaction.

(a) 6 M HCl (dilute)

(b) 6 M H2SO4 (dilute)

(c) 6 M HNO3 (dilute)

(d) 0.6 M H2SO4 (very dilute)

Metals

1. To small strips of zinc and copper, a paper clip (chromium plated iron or steel), and a piece of aluminum foil in the shape of a small cup to hold a small amount of liquid and add the following while noting differences in reactions and rates of reaction.

(a) 6 M HCl (dilute)

(b) 6 M H2SO4 (dilute)

(c) 0.6 M H2SO4 (very dilute)

(d) 6 M NaOH (dilute)

Observe continually (wearing safety glasses!) until a definite reaction has occurred. Beware: you may not initially observe a reaction. Do not lean over the container or remove your safety glasses! Be patient!!2. In the hood, place all of the above metals in 6 M HNO3 (dilute). Caution: Do not put your face close to the wellplate because a poisonous gas may be produced. Do not remove your wellplate from the hood until the evolution of gas has stopped.

Disposal & Clean Up

When your work is complete empty the contents of your wellplate into the container provided. If there are any pieces of marble or metal remaining in your wellplate, try not to let them go down the drain as you rinse your wellplate several times with water. The resulting solution will be neutralized and discarded.

References

1. Brown, Wm.C. and Dubuque, I.A. (1994). Chemistry in Context Laboratory Manual, ACS.2. Conrad, J., Hendrickson, C., Waltz, K. and Pearsall, M.A. (1995). A Lab Produced by CURI. (Piepho, S. ed)

Report format: Reactions of Common Reagents with Everday Materials*Report need to be submitted one week after the practical.

Questions:

PO4 - Ability to analyse, synthesise and integrate knowledge and information

1. Compare the results of the various compounds tested on hair with the control (tap water). Were any of the compounds not harmful to hair? If so, which one(s)?

2. Which material reacted the most with:

(a) 12.5 M sodium hydroxide?

(b) 18 M (concentrated) sulfuric acid?3. Is the polyester or the cotton being disintegrated in the polyester/cotton material when the 18 M H2SO4 is added? What observations and evidence can you use to support your answer?

4. Is sodium hydroxide more reactive with natural (cotton) or synthetic (nylon, polyester)

materials? Give evidence to back up your answer.

5. Which of the fabrics you tested would you recommend as a suitable material for a lab coat? Explain your reasoning?

6. Both bits of aluminum metal and NaOH(s) are constituents of solid Draino, a common draincleaning product. Based on your observations in this lab, why do you think the aluminum is included as a component of Draino?

PO1 : Ability to demonstrate a comprehensive understanding of Biotechnology1. Based on the behavior of nylons with acids and bases, would you say that nylon is an acidic or basic material? Explain your reasoning.

2. You undoubtedly noticed the volume loss when the styrofoam "peanuts" reacted with acetone. If the lost substance was air (and the remaining substance pure polystyrene), what purpose does the air have in the styrofoam "peanuts"?

3. If the concentrated sulfuric acid is extracting water molecules from the sucrose (C12H22O11), what is the black product obtained?

4. The formula for marble is CaCO3. What gas was most likely evolved? And how do you explain its reaction with sulfuric acid?

5. What problems would you anticipate if your bathroom sink had aluminum plumbing?On the basis of your observations, comment on the effectiveness of zinc coatings (galvanized metal) and chromium coatings (old automobile bumpers) as a protection against acid rain. What do these coatings protect iron against?

PRACTICAL 3: ANALYSING ASPIRIN TABLETS (Dr Kathir, you may delete this part and replace with your practical)ObjectivesTo determine the percentage of 2-ethanoylhydroxybenzoic acid (acetylsalicylic acid) in aspirin tablets. Introduction

Aspirin is an analgesic and antipyretic drug. Analgesics are drugs which relieve pain. Antipyretics are drugs which lower body temperature.

The main constituent of aspirin tablets is 2-ethanolhydroxybenzoic acid (acetylsalicylic acid, CH3COOC6H4COOH). The acidic conditions in the stomach do not affect aspirin. However, the alkaline juices in the intestines hydrolyse aspirin to ethanoate (acetate) ions and 2-hydroxybenzoate (salicylate) ions.

CH3COOC6H4COOH + 2OH- CH3COO- + HOC6H4COO- + H2O

Salicylates lower body temperature rapidly and effectively in feverish patients (antipyretic action), but have little effect if the temperature is normal. They are also mild analgesics, relieving certain types of pain such as headaches and rheumatism.

Although toxic dose from salicylates is relatively large, their unctrolled use could be dangerous. Single doses of 5 to 10 g of salicylate have caused death in adults, and 12 g taken over a period of twenty-four hours produced symtoms of poisoning. (A single aspirin tablet containing 0.3 g of acetylsalicylic would produce 0.25 g of salicylate when hydrolysed.)

Principle

A known amount of standard sodium hydroxide solution is used in excess to hydrolyse a known mass of aspirin tablets.CH3COOC6H4COOH + 2NaOH CH3COONa + HOC6H4COONa +H2O

The unused sodium hydroxide which remains is then titrated with standard acid. The amount of alkali required for the hydrolysis can now be calculated and from the above equation, the amount in moles of acetylsalicylic acid which has been hydrolysed can be found.

Equipment/ Apparatus/ Sample Eye protection Aspirin tablet (about 5)

Pipette (25 ml) and safety filler

Burette and stand

Small beaker

2 standard flasks (250 ml)

Conical flask (250 ml)

Small funnel

Bunsen burner

Tripod and gauze/ Hotplate

Approximately 1.0 M sodium hydroxide solution (corrosive) (30 ml)

0.10 M hydrochloric acid (150 ml)

Phenol red/ Phenolphtalein indicatorProcedure1. Using a safety filler, pipette exactly 25 ml of the approximately 1.0M NaOH solution into a 250 ml standard flask and make up to the mark. Now titrate 25 ml of this solution against 0.10 M hydrochloric acid using phenol red (or phenolphthalein) indicator.

2. Carry out one rough and two accurate titrations.a) Record your results in a table similar to the one below.

Titration numberRoughAccurate 1Accurate 2

Final burette reading/ ml

Initial burette reading/ ml

Volume of 0.1 M HCl added/ ml

b) Calculate the accurate concentration, in mol dm-3, of the approximately 1.0 M NaOH.3. Wigh accurately between 1.3 g and 1.7 g of the aspirin tablets into a clean conical flask. (This will be about 5 tblets).

4. Using a safety filler, pipette 25 ml of the approximately 1 M NaOH on to the tablets, followed by about the same volume of distilled water. Simmer the mixture gently on a tripod and gauze over a Bunsen for 10 minutes to hydrolyse the acetylsalicylic acid.

5. Now, cool the mixture and transfer with washings to a 250 ml standard flask and make up to the mark with distilled water.

6. Pipette 25 ml the hydrolysed solution into a conical flask. Titrate this against 0.10 M hydrochloric acid using phenol red (or phenolphthalein) indicator.

References

1) Hill, G., Holman, J. and Holman, J.S. ( ) Chemistry in context: laboratory manual.Report format: Determination of Protein Content

*Report need to be submitted one week after the practical.

Questions:

PO4 - Ability to analyse, synthesize and integrate knowledge and information

1. Record the mass of aspirin tablets taken.2. Record your titration results in a table similar to that in question (a) above.

3. How many moles of NaOH

a) Are added to the flask before hydrolysis of the aspirin,

b) Remain after hydrolysis of the aspirin,

c) Are used in the hydrolysis of the aspirin?

4. How many moles of the acetylsalicylic acid have been hydrolysed?

5. What percentage of the aspirin tablets is acetylsalicylic acid?

6. Look at the packet from which the aspirin tablets came. What mass of acetylsalicylic acid does it say they contain? Compare this with your own results.PO1 : Ability to demonstrate a comprehensive understanding of Biotechnology7. Why is the mixture simmered gently and carefully during hydrolysis? Why is it unwise to boil it vigorously?

8. Why should the washings be transferred carefully to the 250 ml standard flask?

9. What might be the remainder of the tablets be made of?

Neutralisation curing acidity

Introduction

This simple experiment allows students to follow the pH and temperature changes when an acidic solution (vinegar) is gradually neutralised by the addition of slaked lime (calcium hydroxide) and limestone (calcium carbonate). The experiment can be used to explore the issues involved in the control of soil pH in agriculture.

Read our standard health & safety guidance Lesson organisation

The practical work involved is straightforward if the students understand the need for methodical care, and follow the instructions accordingly.

The activity is, perhaps, best suited to more thoughtful students who will appreciate the need for a sequence of repetitive steps to be carried out with care and attention to detail, in order to establish a clear result.

Apparatus and chemicals

Eye protection

Each group of students will require:Beaker (100 cm3)Measuring cylinder (25 cm3)Spotting tile (white plastic, 12 cavities)Glass rodStirring thermometer (-10 C - 110 C) or electronic temperature probe (see note 1) SpatulaUniversal indicator paper (full range, pH 1-14) (see note 2)

Calcium hydroxide, powder (Irritant) (see note 3)Calcium carbonate powder (Low hazard) (see note 3)Vinegar (Low hazard), 20-30 cm3 (see note 4)

Students will also need access to:Universal indicator pH colour chart (Full range pH 1-14)Distilled (or deionised) water, in wash bottles

Technical notes

Calcium hydroxide, powder (Irritant) Refer to CLEAPSS Hazcard 18Calcium carbonate powder (Low hazard) Refer to CLEAPSS Hazcard 19BVinegar (Low hazard) Refer to CLEAPSS Hazcard 38A

1 Stirring thermometers should be able to indicate clearly a rise of about 4C from room temperature. If electronic temperature probes are used instead, they may need to be clamped while students stir the solution with the glass rods.

2 Indicator paper is expensive, so it would make sense to pre-cut the paper into smaller test pieces. Each group of students will need 12 pieces to fit into the cavities in the spotting tile.

3 Each group of students will need a small container (e.g. small beaker or watch glass) of calcium hydroxide powder (also labelled as slaked lime and Irritant) and another of calcium carbonate powder (also labelled as ground limestone). Students need at least 6 spatula measures of each solid.

4 Distilled (colourless) malt vinegar is required, as the colouring in ordinary malt vinegar would obscure the indicator colours. The concentration of the vinegar should be checked before the lesson, and adjusted if necessary, to ensure that the addition of 6 successive spatula measures of slaked lime produces a clear sequence of pH changes, and no further change between the final two spatula measures. The vinegar can be provided in a small (labelled) beaker.

Procedure

a Place a piece of Universal indicator paper in each of the hollows on the spotting tile.

b Measure 10 cm3 of vinegar into the beaker and add 10 cm3 of water. Stir to mix. Recordthe temperature of this vinegar solution.

c Use the glass rod to take a drop of the vinegar solution and place it onto the first piece of indicator paper on the spotting tile. Compare the colour with the indicator chart and record the pH.

d Add a spatula measure of slaked lime to the vinegar solution and stir steadily for 10 seconds. Record the new temperature of the solution. Take a drop of the solution andplace on the second piece of indicator paper on the spotting tile. Make sure you do nottransfer solid particles of slaked lime. Record the pH found.

e Repeat the procedure five more times, with one more spatula measure of slaked limeeach time, for five more pieces of indicator paper. Record the temperature of the solutionand the pH each time.

f Rinse out the beaker, glass rod and thermometer. Repeat steps a e using groundlimestone instead of slaked lime.

Teaching notes

The intention of this experiment is to reinforce the idea that pH changes steadily over the pH range as an acid, such as the ethanoic (acetic) acid in vinegar, is neutralised by an alkali such as slaked lime. Indeed, the pH will end up on the alkaline side when excess alkali is added.

The first part, using slaked lime, should take about 20-30 minutes, while the second part should not add more than 15 minutes of practical work.

The measurement of the temperature rise is intended solely as an introduction to the idea of energy changes accompanying chemical changes. In this case, the temperature rise (about 4C) is not large enough for most students to notice without the use of a thermometer or temperature probe.

The evolution of gas (carbon dioxide) with ground limestone should be noticeable (fizzing). At this time, this is probably best just noted as an interesting event and need not be followed up until later.

The other difference from slaked lime is more important here: whereas slaked lime takes the pH across to a moderately alkaline value (pH about 10 may be expected), ground limestone should take the pH change only as far as about 7 (roughly neutral). This should be checked before the lesson, in case any impurities in the ground limestone might lead to an alkaline result.The use of lime in agriculture has of course more complex reasons than just a matter of adjusting pH. But at this stage, it is the adjustment of the pH of soil that is the target idea. Slaked lime has a more rapid effect on soil pH, but care may be needed not to add too much and make the soil too alkaline. However ground limestone, although slower in its effect, will only take the pH to neutral, and any surplus added will simply help to retain the pH around neutral for some time afterwards.

Spontaneous exothermic reaction

In this demonstration experiment, a mixture of glycerol (propane-1,2,3-triol) and potassium manganate(VII) crystals bursts into flame, giving off clouds of steam, after a short time lag.

Read our standard health & safety guidance Lesson organisation

This reaction can be used as a fun demonstration to show a spontaneous reaction, or as an example of the redox reaction between a fuel and a powerful oxidising agent.

The time lag illustrates the speeding up of an initially slow exothermic reaction as the energy given out raises the temperature of the mixture.

Apparatus and Chemicals

Eye protection

The teacher requires:Safety screensClean metal lid from a tin can or jar (see note 1)Heat resistant mat

The quantities of chemicals given are for one demonstration.

Access to:Potassium manganate(Vll) (Oxidising agent, Harmful, Dangerous to the environment), 2-3 g in the form of fine crystals (see note 2)Glycerol (propane-1,2,3-triol) (Low hazard), about 1 cm3 in a test-tube (see note 3)

Technical notes

Potassium manganate(VII) (Oxidising agent, Harmful, Dangerous for the environment) Refer to CLEAPSS Hazcard 81Glycerol (propane-1,2,3-triol) (Low hazard) Refer to CLEAPSS Hazcard 37

1 If the lid from a jar has a plastic lining, this should be scraped off. Alternatively, use a small foil cake case which has been cleaned and dried.

2 Fine crystals of potassium manganate(VII) work much better than larger ones. Use a pestle to grind large crystals in a clean mortar, if necessary.

3 Old samples of glycerol are sometimes ineffective, possibly because of absorbed water from the air.

Procedure

HEALTH & SAFETY: Wear eye protection (teacher and students). Use safety screens.

a Put 2-3 g of potassium manganate(VII) in a small pile on the tin lid standing on the heatproof mat. Make a small hollow in the centre of the pile.

b Pour about 1 cm3 of glycerol into the hollow in the pile of potassium manganate(VII).

It is sometimes better if the glycerol is warmed just before use. After about 20 seconds (but beware it can be much longer), the mixture starts to give off steam. The glycerol in the mixture then ignites, burning with a bright, pinkish (lilac) flame for a few seconds more, leaving a dark brown or black residue.

Teaching notes

Eye protection and safety screens are essential. Small particles of potassium manganate(VII) may fly out.

A white background is useful. The reaction is even more spectacular in a darkened room.

Point out that the pink (lilac) colour of the flame is characteristic of potassium salts.

Redox chemistry

At advanced level, the redox nature of the reaction can be explored. Do this by allowing the residue to cool down and then dissolving it in water. This produces a green solution suggesting the presence of a Mn(Vl) species, as well as a brown solid, manganese(lV) oxide. This confirms the reduction of the manganate(Vll) ion; the glycerol has been oxidised to water (hence the steam) and carbon dioxide.

Chemicals from seawater

This experiment is a simple one to carry out and is designed to show that seawater contains a mixture of different salts. It can be used in conjunction with Earth Science topics linked to the conveyance of mineral salts into the sea via rivers.

This experiment could be carried out early in a science course while using scientific apparatus is still a novelty, because it provides practice at using a variety of equipment and also introduces the concept of a mixture and some simple chemical tests. It is also an opportunity to reinforce safety messages eg wearing eye protection throughout and activity and the need to keep standing up.

Read our standard health & safety guidance Lesson organisation

The experiment can be carried by groups of two or three and will take about one hour to complete.

Apparatus and chemicals

Eye protectionBeaker (250 cm3)Beaker (100 cm3)Conical flask (100 cm3)Filter funnelFilter paperBunsen burnerHeat resistant matTripodGauzeTeat pipette

Seawater, 200 cm3 (see note 1)Access to hydrochloric acid, 1 mol dm-3 (Low hazard at this concentration)

Technical notes

Hydrochloric acid (Low hazard at concentration used) Refer to CLEAPSS Hazcard 47A and Recipe card 31Limewater (Low hazard) Refer to CLEAPSS Hazcard 18 and Recipe card 15Calcium sulfate (Low hazard) Refer to CLEAPSS Hazcard 19BSodium chloride (Low hazard) refer to CLEAPSS Hazcard 47B

1 Although it is tempting to use genuine seawater if available, this experiment is usually more successful if the seawater is generated artificially. Genuine seawater will not always yield a full range of solids in sufficient quantities to be detected. Artificial seawater can be generated by adopting the following procedure:

Bubble carbon dioxide through a mixture of 250 cm3 limewater (Low hazard) plus 750 cm3 deionised water for about 20 minutes or until the cloudy precipitate disappears completely. Filter. Add as much solid hydrated calcium sulfate (Low hazard) as will dissolve. Add about 15 g of sodium chloride (Low hazard). Stir until all the solid has dissolved, leave to settle and then decant the liquid if necessary.

Procedure

HEALTH & SAFETY: Wear eye protection throughout. Take care with hot apparatus and solutions.

a Place 200 cm3 of seawater in a 250 cm3 beaker.

b Heat and boil the seawater.

c Stop heating when about 60-70 cm3 of liquid remains. Solid will be precipitated during this evaporation process.

d Allow to cool and for any solids to settle.

e Pour the clear liquid into the 100 cm3 beaker, leaving the solids behind.

f Add a few drops of hydrochloric acid to the solids left behind and observe what happens.

g Put the 100 cm3 beaker on the tripod and gauze and heat the liquid until another solid appears. This will occur when about 30-40 cm3 of liquid remains.

h Carefully filter the liquid into the conical flask.

i Wash out the 100 cm3 beaker and pour the filtrate into the beaker.

j Boil the liquid yet again until there is almost none left.

k Let it cool and note what is observed.

Teaching notes

Encourage the students to write down what they observe at each stage.

Teachers may wish to mark 250 cm3 beakers at the 60 cm3 level if there are no gradations already present.

The artificial seawater contains calcium hydrogencarbonate owing to the reaction of limewater with excess carbon dioxide:

Ca(OH)2 (aq) + 2CO2(g) Ca(HCO3)2(aq)

When this solution is boiled it soon precipitates calcium carbonate:

Ca(HCO3)2(aq) CaCO3(s) + CO2(g) + H2O(l)

This is the identity of the predominant solid first left behind when the liquid is boiled. However, some calcium sulfate will also be present.

When hydrochloric acid is added to this solid, students should observe effervescence (fizzing), since the calcium carbonate is producing carbon dioxide gas:

CaCO3(s) + 2HCl(aq) CaCl2(aq) + CO2(g) + H2O(l)

The solid which continuously crystallises out on further evaporation is sparingly soluble calcium sulfate, which is the predominant solid filtered off when 30 cm3 of sea water remains.

The more soluble sodium chloride precipitates out during the final stages of evaporation.

Student questionsHere are some questions for students.

a What evidence is there that seawater is a mixture of salts?

b What gas is likely to have been evolved when hydrochloric acid is added to the solids first collected?

c What does this tell you about the identity of these solids?

d Research the web to try to find information about the solubilities of sodium chloride and calcium sulfate two common compounds present in seawater. Use this information to predict the possible identity of the very last solid left at the end of your experiment.

NAME : ___________________________________________________________________

MATRIC NO : ___________________________________ BATCH : ____________________

Department of Biotechnology,

Faculty of Applied Sciences,

AIMST UNIVERSITY

A glycerol (a non-ionic detergent)

A sodium alkylbenzene sulfonate

A sodium alkyl sulphate

Figure 1. A diagram of a soap micelle surrounded by water molecules. The lines in the center represent grease and oil.

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