Question

1. Pour a small amount of the red cabbage indicator liquid into each of the seven cups of different liquids. Add just enough indicator until you see a color change. Record your observations, and rank them based on their pH, using this scale: 1 = lowest pH, 7 = highest pH Solution Colour Cabbage Colour pH Ranking lemon juice baking soda milk vinegar soda Windex water

Answer 1

Answer:

Materials List

Each group needs:

eight 5-ounce (~148 ml) paper cups, containing vinegar, lemon juice, milk, 7-Up or Sprite, baking soda, Windex, and red cabbage juice indicator (prepared by teacher, see below), respectively

7 pH indicator strips

Red Cabbage Chemistry Worksheet, one per student

For the teacher (to prepare group materials; instructions in Procedure section):

2 red cabbages

large pot, water, stove, strainer

pitcher or jug, to hold red cabbage indicator from pot

marker, to label paper cups

tablespoon, to measure baking soda

extra 5-ounce paper cups, to double-up on the Windex cups

the seven test items (as listed above), enough for all teams

Students take advantage of the natural ability of red cabbage juice to perform as a pH indicator to test the pH of seven common household liquids. Then they evaluate the accuracy of the red cabbage indicator, by testing the pH of the liquids using an engineer-designed tool, pH indicator strips. Like environmental engineers working on water remediation or water treatment projects, understanding the chemical properties (including pH) of contaminants is important for safeguarding the health of environmental water sources and systems.