Question

What is the pH of a solution with a hydroxide ion concentration of 10–6M?

A. pH = 8
B. pH = 7
C. pH = 6
D. pH = 12

Answer 1

pOH = - log₁₀[OH]

pOH = - log₁₀[10⁻⁶]

pOH = - (-6) = 6

But pOH + pH = 14

6 + pH = 14

pH = 14 - 6 = 8

pH = 8

Option A.

Answer 2

[OH-] = 1 X 10^-6 M = 10^-6 M

pOH = -log [OH-] = -log 10^-6 = 6

and as pH + pOH = 14

so pH = 14 - pOH = 14 - 6 = 8

the answer is A hope this helps :D