What is the pOH of a 50.0 mL solution of 0.050 M HClO4? What is the pH of the solution?

Question

I'm stuck on this question. Help would be greatly appreciated!

Answer 1

Hello, Kai,

HClO₄ is perchloric acid, and is a strong acid. That means that it will dissolve completely in water. Since it is at 0.050 M, the hydrogen ion concentration (expressed as [H⁺] or [H₃O⁺]) will also be 0.05M. pH is defined as the negative log of the hydrogen ion concentration:

[H₃O⁺] = 5x10^-2

log [H₃O⁺] = -1.3

-log [H₃O⁺] = 1.3

pH = 1.3

In water, [H₃O⁺]*[OH^-] = 10^-14

This means the sum of pH and pOH will be 14. If pH is 1.3, pOH will be 12.7.

The volume makes no difference here. Just the concentration.

Bob