Purpose: To prepare soap from different fats and determine if there is a difference between soap and detergent.

Dissolve 5 g NaOH in 10 mL distilled water. Caution: the solution will become very hot. Add 20 mL of 95% ethanol to the NaOH solution in a beaker. Weigh by difference 5 g of Crisco or other fat in a 150 mL beaker. Add the fat and several boiling stones to the alcoholic solution. Cover the beaker with a watch glass and boil on a hot plate in the hood for about 30 minutes. While waiting for the solution to boil, prepare a solution of 25 g NaCl in 80 mL water. After boiling the solution for 30 minutes, it should be clear but may have color. Remove the solution from the hot plate and allow it to cool for about 10 minutes. Add the salt solution to the soap solution, stir thoroughly. Allow the solution to stand for 10 minutes. Filter by gravity through pleated filter paper.

Properties:

Prepare a solution of 1 g of soap from above in 50 mL boiling water. Prepare similar solutions of a commercial soap and detergent.

Test each with pH paper.

Emulsifying properties:

Place 3 drops of mineral oil in each of four test tubes. Add 5 mL of distilled water to the first, 5 mL of your solution to the second, 5 mL of the commercial soap to the third test tube and 5 mL of the detergent to the fourth test tube. Cover and shake for 1 minute. Record your observations.

Place 5 mL of your soap solution in 3 test tubes. Add 2 mL of 1% CaCl₂ to the first, 1% MgCl₂ to the second and 1% FeCl₃ to the last. Record your results.