What is the pOH of a solution...

Question

What is the pOH of a solution that contains [H3O+] of 3.10 x 10^-9 M ?

a.8.49

b.6.49

c.7.49

d.5.49

Answer 1

There are 2 ways to solve this problem.

Method 1: Convert [H₃O⁺] to pH, then calculate the pOH.

Method 2: Convert [H₃O⁺] to [OH^-], then calculate the pOH.

I will opt for method 1.

pH = -log [H₃O⁺] = - log 3.10 x 10^-9 = 8.51

14.00 = pH + pOH

pOH = 14.00 - pH = 14.00 - 8.51 = 5.49 (answer choice d)