ISCI 2002 GU Complete Short Science Worksheet

Acid/Base ChemistryLaboratory Exercises for ISCI 2002
Acid: a proton (H+) donor Base: a proton acceptor [usually results in hydroxide (OH-) in aqueous
solution]
Water acts as both an acid and a base (or, undergoes self-ionization in pure water):
H2O +H2O
H3O+ + OH─ or H2O
H+ + OH─
H+ concentration and OH─ concentration in pure water are equal, pH=7.
In ACIDIC solutions, H+ concentration is greater than OH─ concentration, pH7.
For this experiment, we will test several common household items for their acid/base chemical
characteristic. We will use two different “indicators” to identify the acidity or basicity of the solutions.
Indicator 1: Prepare the red cabbage indicator according to the instructions below the table.
Indicator 2 OPTIONAL: You can probably get a few pieces from a local school chemistry or biology
teacher. Litmus paper is made from a lichen-derived dye (use just a small piece of a strip for each
Test Solution).
PROCEDURE: Prepare each Test Solution as directed [if you have the materials available – test at
least 5 solutions]. Test the solutions with the red cabbage indicator by adding 5 mL (1 tsp) of the
indicator to 15 mL (1 Tbs) of the Test Solution. Test the solutions with the litmus by dipping a piece
of a litmus strips (one “Red” [pink] and one “Blue” [purple] strip) in the prepared Test Solution.
Use the blanks for additional test solutions of your choice.
Test Solution
Result with Red Cabbage
Result with Red/Blue Litmus Paper
EXAMPLE: ¼ tsp drain cleaner 25 mL in water
Blue-Green
Red turned blue/Blue stayed blue
1 tsp household ammonia in 25 mL water
1 tsp baking soda dissolved in 25 mL water
1 tsp table salt dissolved in 25 mL water
1 tsp table sugar dissolved in 25 mL water
1 tsp vinegar dissolved in 25 mL water
1 antacid tablet dissolved in 25 mL water
¼ tsp muriatic acid dissolved in 25 mL water
1 tsp lemon juice dissolved in 25 mL water
Directions for preparing red cabbage indicator: Chop the red cabbage into small pieces until you have about 2 cups
of cabbage. Place it in a large glass container & add boiling water to cover the cabbage. Allow at least ten minutes for
the color to leach out of the cabbage. Alternatively, you can place about 2 cups of cabbage in a blender, cover it with
boiling water, and blend it. Filter out the plant material to obtain a red-purple-bluish colored liquid.