Question

1) Two clear solutions are placed in separate beakers. The first solution has a pH = 4, and the pH of the second solution is unknown. If the two solutions are mixed and the resulting solution has a pH = 7, describe the second solution.

Answer 1

pH = 10

Step-by-step explanation:

pH = -log [H⁺]

A solution that is pH = 4 has a [H⁺] = 1x10⁻⁴M

As the mixture of the two solutions is pH = 7 (Neutral). The second solution must contain the exact amount of OH⁻ to neutralize the H⁺ of the first solution. That is [OH⁻] 1x10⁻⁴

And as pOH = -log [OH⁻]

pOH = -log 1x10⁻⁴

pOH = 4

Also, pH = 14-pOH

pH of the second solution must be:

14 - 4

pH = 10