Answer to Question #117963 in General Chemistry for george

Question

Determine the [H+] and [OH-] in
(a) 5.0 x 10-5 M HNO3
(b) 2.0 x 10-6 M KOH

Answer 1

(a) As HNO3 is a strong acid, it dissociates completely. As a result, [H+] = [HNO3] = 5.0 × 10^-5 M. As [H⁺] × [OH^-] = 1.0 × 10^-14 :

[OH-] = 1.0 × 10^-14 / [H⁺] = 1.0 × 10^-14 M / 5.0 × 10^-5 = 2.0 × 10^-10 M

(b) As KOH is a strong acid, it dissociates completely. As a result, [OH^-] = [KOH] = 2.0 × 10^-6 M.

[H⁺] = 1.0 × 10^-14 / [OH^-] = 1.0 × 10^-14 / 2.0 × 10^-6 = 5.0 × 10^-9 M

Answer: (a) [H+] = 5.0 × 10^-5 M, [OH-] = 2.0 × 10^-10 M; (b) [OH-] = 2.0 × 10^-6 M, [H+] = 5.0 × 10^-9.