Fight Club Lab

bFight Club Lab

Problem: How is soap made? How does soap clean soiled articles? How does soap made in the laboratory compare to commercially-prepared soap?

Introduction: Soap is something that we regularly buy in the grocery store and use daily. This was not always the case. Queen Isabella of Spain (1451-1504) claimed that she had bathed twice in her entire life, once when she was born and again on her wedding day. Queen Elizabeth I of England (1558-1603) took a bath every three months whether she “needeth it or no”. Cleopatra, the beautiful queen of Egypt bathed in fragrant oils. The oils softened her skin, and the perfumes were needed to camouflage the odors produced by the bacteria on her skin. Soap was known in ancient Rome—a soap factory was revealed among the ruins of ancient Pompeii—but this soap was too harsh to use on skin.

The use of soap and water as we know it began in London when people realized that poor personal hygiene was part of the cause of cholera and typhoid epidemics. In 1846, the British government passed a Public Baths and Wash Act. It provided public baths and laundries for the working class of London. The idea rapidly spread throughout Europe and the United States.

Soap is produced when a fat (or oil) is mixed and heated with sodium hydroxide, commonly known as lye, in a chemical process called saponification. Solid soap is the sodium salt of a fatty acid. Soft soap is a mixture of soap and glycerol. Liquid soap is the potassium salt of a fatty acid.

In this experiment you will synthesize soap and then analyze its properties through several different chemical tests.

Pre-Lab Questions:

1. What are the properties of soap that you use at home? What functions do you expect your soap to perform? Describe what you expect from hand soap or detergent that washes your clothes.

2. Many organic compounds are nonpolar. Will these compounds be soluble in water? Why or why not? (remember the saying like dissolves like)

Procedure:

1. Weigh out 15-20 g of your selected oil or fat on a piece of weighing paper. (coconut oil, lard or vegetable shortening). Transfer it to a 400 mL (large) beaker. Throw away the weighing paper.

2. Weigh 8 g of NaOH to a weighing dish and place in the 250 mL (small) beaker.  Replace the weighing dish.

3. Measure 25 mL of H₂O in the larger graduated cylinder and to the NaOH and mix until completely dissolved.

4. Add your NaOH mixture to your 400 mL beaker that contains your fat.

5. Measure 10 mL of ethyl alcohol using small graduated cylinder. Add this to the 250 mL beaker containing the fat and NaOH solution.

6. Heat the mixture carefully on the heating unit on low to medium heat, stirring it CONSTANTLY for at least 20 minutes. The solution should be HOT BUT NOT BOILING.  If it looks like it will boil, take the beaker off using the beaker tongs and turn down the heat on your hot plate.

7. After 20 minutes, carefully drip in 10 mL of additional ethyl alcohol. Stir it well. As the mixture is heated, it will bubble and foam. Be careful to regulate your mixture by moving it as necessary from the heat to prevent the mixture from overflowing.

8. Then after another 20 minutes, add 25 mL of water and continue heating and stirring for an additional 10 minutes.

9. After the 10 minutes, remove from the heating unit. Allow the mixture to cool.

10. Remove the coagulated soap mass with your spoon. Using a paper towel; shape it into a bar or a ball. You may place it in a mold if you like to shape your soap. Place it on several layers of paper towel and label the paper towel with your group members name. Observe and record its smell and appearance.

11. Allow the soap to air dry until the next laboratory session.

Procedure: Part 2 Testing the Soap

1.  Place 10 mL of water in each of the three test tubes. Add 0.5 g of your soap to your first test tube. Stopper the tube and shake vigorously to test the foaming action of your soap. Repeat this process using commercial soap in the second test tube and commercial detergent in the third test tube. Use 0.5 g of soap each test. Record your observations. Put your test tube to the side and arrange them in order to not mix them up.

2.  Add 2-3 drops of phenolphthalein indicator solution to your first prepared test tube. Shake and record your observations. Repeat this process using commercial soap in the second test tube and commercial detergent in the third test tube. Record your observations. Clean out the test tubes. (Reminder: phenolphthalein turns dark pink in strong base and light pink in weak base. It is clear in neutral and acidic solutions.) Clean out the test tubes at the sink with a test tube brush.

3. Place 10 mL of water in each of the three test tubes. Add 8-10 drops of vegetable oil to each tube. Note that the oil forms a separate layer on top of the water. Stopper and shake the first tube. Add a 0.5 g of your soap to the first test tube. Stopper the tube and shake till all the soap is dissolved. Allow the tube to stand a few minutes and move on to prepare a 2^nd test tube.  Repeat this process using commercial soap in the second test tube and commercial detergent in the third test tube. After allowing the test tubes to sit, observe how much oil remains in each of the test tubes. Record your observations. Clean out the test tubes.

4. Place 10 mL of water in each of the three test tubes. Add a 0.5 g of your soap to the first test tube. Stopper the tube and shake to dissolve the soap. Add 10-12 drops of CaCl₂ solution to the soap solution. Shake and record the results. Repeat this process using commercial soap in the second test tube and commercial detergent in the third test tube. Record your observations. Clean out the test tubes.

Data:

	Test Tube #1: Your soap	Test tube #2: Commercial soap	Test tube #3: Commercial detergent
Color, texture and appearance of the soap:
Sudsing test:
Phenolphthalein test
Oil test:
Calcium chloride test:

Analysis:

1. How do the sudsing actions of the soaps (both yours and commercial soap) and detergent compare?

2. How do the oil breakup capabilities of the soaps and detergent compare?

3. Calcium chloride releases calcium ions in the water. This makes the water “hard”. How do the results of the soaps and detergent compare in hard water?

4. How do the pH values of the commercial soap and detergent compare with your soap?

5. In the lab used fats and oils to make your soap and they are organic compounds.  What are some of the properties of organic compounds that you can hypothesize from working with the fat. (Hint: think about the properties we have studied about elements such as boiling point, density.)

6. How did your soap compare to the soap from the store? Do you think it as good at those you purchase? Explain why or why not.