Calculate the H3O+ concentration present in water under the following conditions. Enter your answer in scientific notation.

Question

a. [OH^-] = 8.3 x 10^-9 M

b. [OH^-] = 7.4 x 10^-2 M

c. [OH^-] = 4.3 x 10^-10 M

Answer 1

Recall:

[H3O⁺][OH^-] = 1x10^-14 = Kw

Solving for [H3O⁺] we have

[H3O⁺] = 1x10^-14/[OH-]

(a) [H3O⁺] = 1x10^-14 / 8.3x10^-9 = 1.2x10^-6 M

do (b) and (c) the same way.