Question

Scenario: You are testing two different household solutions with your cabbage indicator, using the color key to the right.

The second solution turns purple. A possible hydrogen ion concentration for this solution is:

1 × 10-2 M

7× 10-3 M

1 × 10-7 M

7 × 10-4 M

Answer 1

1 × 10^-7 M

Purple corresponds to about pH 7 (neutral). pH = −log[H+], so [H+] = 10^−7 M.