Part II Materials

12 small droppers of each of the following:
0.1 M Hydrochloric acid, HCl
0.1 M Sodium hydroxide, NaOH
Distilled (or deionized) water
Universal indicator
12 Well-plates or 120 small test tubes (can clean ones used previously)
60 Toothpicks or small stirring rods

Part III Materials

12 small droppers of each of the following:
A number of commercial samples, e.g., household ammonia (See Advance Preparation)
Universal indicator
Distilled (or deionized) water
Well-plate, or small test tube for each commercial product tested
Conductivity tester (Directions for building a conductivity apparatus are given in the Instrumentation section of this module.)
Scissors

Advance Preparation

Each student pair should have one dropper bottle of each of these:

• 0.1 M H2SO4 - Add 1.5 mL of concentrated (18 M) sulfuric acid, H2SO4, to enough water to make 250 mL of solution. Warning: Be sure to add acid slowly with continual stirring to several hundred milliliters of water, then make up to 500 mL of solution.

• Indicators - Bromthymol blue, phenolphthalein, and universal indicator may be purchased as previously-prepared solutions from appropriate commercial vendors. Feenamint(TM) and Ex-Lax(TM) are alternative sources of phenolphthalein. Each group should have one dropper bottle of each indicator.

• A group of household or commercial samples spanning a wide range of pH. Suggestions, with approximate pH values in parentheses, include: liquid Vanish(TM) (pH 1), solid Vanish(TM) (pH 2), vinegar (pH 3), Sprite(TM) (pH 3), orange juice (pH 4), most vinyl cleaners (pH 4), Fluoriguard(TM) anti-cavity rinse (pH 5), Cepastat(TM) Mouth Spray (pH 5), most nail polish removers (pH 6), many shampoos (pH 6), many liquid detergents (pH 7 and above), borax solution (pH 9), window cleaner such as Windex(TM) (pH 10), Dow(TM) bathroom cleanser (pH 11), many dishwashing detergents (pH 12), Drano(TM) (pH 14).

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