What is the hydronium ion concentration of a solution that has an hydroxide ion concentration of 1.0 x10–3 M? A. 1.0 x10–14 M B. 1.0 x10–11 M C. 1.0 x10–7 M D. 1.0 x10–3 M

Question

What is the hydronium ion concentration of a solution that has an hydroxide ion concentration of 1.0 x10^–3 M?

A. 1.0 x10^–14 M

B. 1.0 x10^–11 M

C. 1.0 x10^–7 M

D. 1.0 x10^–3 M

Answer 1

[H3O⁺][OH^-] = 1x10^-14 (the autoionization constant for water)

Solving this for [H₃O⁺] we have...

[H₃O⁺] = 1x10^-14 / 1x10^-3 = 1x10^-11 M (ANSWER B)

Answer 2

If the solution is neutral it must be D. Because hydronium H₃ O⁺ ions are formed when a water molecule loses a proton to form a hydroxide ion, so the concentration of both ions must be the same.