Question

Calculate the pH of an aqueous solution containing 6.02x10^20 hydronium (H3O+) ions per liter.

Answer 1

Aqueous solution containing 6.02 x 10²⁰ hydronium (H₃O⁺) ions.

Since 6.02 x 10²³ atoms (avogrado's number) of H₃O⁺ = 1 mole

So,

(6.02 x 10²⁰ atoms) / (6.02 x 10²³ atoms/mole) = 1 x 10^-3 mole of H₃O⁺

Now, Molarity = moles / Liter

Molarity of H₃O⁺ = 1 x 10^-3 mole / 1 Liter

                               = 1 x 10^-3 M

[H₃O⁺] = 1 x 10^-3 M

pH = -log [H₃O⁺] = - log (1 x 10^-3) = 3