Chapter 6 Ions: Charged Particles in Solution 75 Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website. Name ________________________________________________________________ Date ________________________ Period _______________ Activity E Lab: Red Cabbage as an Acid-Base Indicator Safety • Dispose of chemical solutions in the sink and flush all glassware with plenty of water. • Wear splash goggles when titrating acids and bases. • Do not taste the solutions. Purpose Before the twentieth century, if you wanted to know how acidic or basic a substance was, you would test it with natural indicators. In the scientific world, the most commonly used natural indicator is litmus. Many food products also have color pigments that make good indicators of acid and base levels. In this experiment, you will use red cabbage juice to make your own acid-base scale. You will use the red cabbage juice as a natural indicator to determine whether the variety of products commonly found in the home are acids or bases. Then you will confirm your results using pH indicator paper or a pH meter. Equipment 2 burets buret stand 25 test-tubes with lids or stoppers wax pencil test-tube rack 15-mL metric measuring spoon pH indicator paper or pH meter Supplies 0.5 M solution of sodium hydroxide (NaOH) acetic acid 250 mL fruit juice 15 mL baking soda 15 mL buttermilk 15 mL milk 15 mL bleach 15 mL clear soda 15 mL egg white 15 mL dishwashing liquid solution 15 mL honey 15 mL lemon juice 15 mL milk of magnesia 15 mL tea 15 mL ammonia solution Procedure Part I 1. Use the wax pencil to number 12 test tubes from 1 to 12 and place them in a test-tube rack. 2. Dispense sodium hydroxide (NaOH) and acetic acid from burets into the 12 numbered test tubes as specified in the data table. 3. Measure 10 mL of the natural indicator (red cabbage juice) into each test tube. 4. Cover each test tube with a lid or stopper and shake gently 2 to 3 times to combine.