For a change of pace, let\'s try a hands-on laboratory experiment involving comm
ID: 851416 • Letter: F
Question
For a change of pace, let's try a hands-on laboratory experiment involving common household items that you either have at home or can easily purchase in a supermarket. Page 168 of the textbook explains how red cabbage can be used as an acidâbase indicator to find the pH of a solution. In this experiment you will make the cabbage juice at home and try it out on different household items. To conduct the experiment, you will need the following: A small head of red cabbage Vinegar Household ammonia Six (6) different household items to use as samples (e.g., salt, detergent, lemon juice, soap, etc.) Colored items are not suitable, and above all, do not use any dangerous, flammable, or highly caustic samples. In a blender, blend about ݽ of a small head of red cabbage (or ݼ of a larger head) and 3 cups of water. With a sieve, filter out the cabbage, and save the juice. You will have about 3 cups of cabbage juice. Take three clear drinking glasses (colored glasses are not suitable), and pour 2 ounces of the cabbage juice into each glass. Add 3 tablespoons of vinegar to glass 1 (this establishes the color of cabbage juice for an acid); add 3 tablespoons of water to glass 2 (this establishes the color for a neutral solution); and add 3 tablespoons of ammonia to glass 3 (this establishes the color for a base). Set the glasses aside for comparison. In six similar glassesâor one glass washed after each sampleâadd 2 ounces of the cabbage juice and 1â3 tablespoons of a different household sample. After adding each sample, compare its color with the three glasses used to establish the color of acid, neutral, and base. Decide which substances are acidic, basic, or neutral, and record your results
Explanation / Answer
Add 3 tablespoons of vinegar to glass 1 (this establishes the color of cabbage juice for an acid); add 3 tablespoons of water to glass 2 (this establishes the color for a neutral solution); and add 3 tablespoons of ammonia to glass 3 (this establishes the color for a base).
The colour of cabbage juice for an acid - Red, purple or violet
The colour of cabbage juice for a base - blue- blue greeninsh or greenish yellow at high pH
The colour of cabbage juice for neutral - red-purple-bluish
On adding vinegar or lemon juice- colour changes to red
On adding ammonia or egg white- colour changes to blue or green
On adding distilled water or vegetable oil- colour remains the same