If the OH‑ ion concentration in an aqueous solution at 25.0 °C is 6.6 x 10‑4 M, what is the molarity of the H+ ion?

1.5 × 10⁻¹¹ M

Explanation:

Step 1: Given data

Step 2: Consider the self-ionization of water

H₂O(l) ⇄ H⁺(aq) + OH⁻(aq)

Step 3: Calculate the molar concentration of H⁺

We will use the equilibrium constant for the self-ionization of water (Kw).

Kw = 1.0 × 10⁻¹⁴ = [H⁺] × [OH⁻]

[H⁺] = 1.0 × 10⁻¹⁴ / [OH⁻]

[H⁺] = 1.0 × 10⁻¹⁴ / 6.6 × 10⁻⁴

[H⁺] = 1.5 × 10⁻¹¹ M