Question

What is the pH of a KOH solution that has [H+] = 1.87 × 10–13 M? Round to the nearest tenth.

What is the pOH of a KOH solution that has [OH–] = 5.81 ×10–3M? Round to the nearest hundredth.

What is the pH of a solution of NaCl that has [H+] = 1.00 × 10–7 M? Round to the nearest hundredth.

Answer 1

Use pH = -log[H+] and pOH = -log[OH^-].

1) pH = -log(1.87×10^-13) = 13 - log(1.87) ≈ 12.7 (to nearest tenth)

2) pOH = -log(5.81×10^-3) = 3 - log(5.81) ≈ 2.24 (to nearest hundredth)

3) pH = -log(1.00×10^-7) = 7.00 (to nearest hundredth)