Given [OH-] = 5.5 x 10-10M Find: [H3O+] and pH Is this acidic, basic or neutral?

The hydroxyl ion concentration of the solution [OH⁻] is 5.5 x 10⁻¹⁰M

Problem:

To find [H₃O⁺] and the pH of the solution:

We know that the ionic product of water has been experimentally determined and it is given for a pure water as 1.0 x 10⁻¹⁴mol²dm⁻⁶ at 25°C.

So : [H₃O⁺][OH⁻] = 10⁻¹⁴mol²dm⁻⁶ at 25°C

To find the concentration of the hydroxonium ions:

[H₃O⁺] = [10⁻¹⁴] / [OH⁻]

[H₃O⁺] = 10⁻¹⁴ / 5.5 x 10⁻¹⁰ = 1.8 x 10⁻⁵M

To find the pH of the solution, we know that;

pH = - log[H₃O⁺] = - log 1.8 x 10⁻⁵ = 4.74

The solution is acidic