What are the molar concentrations of H3O+ and OH- in a solution that has a pH of 9.85?

Question

What are the molar concentrations of H₃O⁺ and OH^- in a solution that has a pH of 9.85? Show your work. 

Answer 1

pH = -log [H₃O⁺]

pOH = -log [OH^-]

pH + pOH = 14

pH = 9.85

pOH = 14 - 9.85 = 4.15

For pH = 9.85, [H₃O⁺] = 1x10^-9.85 = 1.41x10^-10 M

For pOH = 4.15, [OH^-] = 1x10^-4.15 = 7.08x10^-5 M