Time is needed to pour each of the substances into bottles for individual lab stations. If the red cabbage juice from the Electrophoresis activity has been stored at room temperature, there may be a need to boil more red cabbage to make the indicator.
The purpose of this activity is for students to make a connection between household acids and bases and the ions created in the electrophoresis gel box (see Electrophoresis activity). The fact that the pH indicator changes to the same colors as it would in an acid or a base indicates to the student that ionic charges are a part of acids and bases.
This activity with the lecture should only take one class period.
The baking soda solution should be a saturated solution.
To make the red cabbage juice indicator boil the red cabbage in water until the water becomes dark purple. Let it cool before using.
At each lab station set up the small bowl, a bottle each of cabbage juice, lemon juice, vinegar, baking soda solution, water, and alcohol.