An ammonia solution has a pH of 11.30, what is the H₃O⁺ concentration in this solution?

Question

Quizplus · Accepted Answer

The pH of a solution of ammonia is related to the concentration of hydroxide ions (OH-) present in the solution through the equation: pH = 14 - pOH. Since ammonia acts as a base in water, it accepts a proton (H+) from water to form ammonium ion (NH4+) and hydroxide ion (OH-). This means that in the solution, the concentration of hydroxide ions can be calculated using the relationship: [OH-] = Kw/[NH3], where Kw is the ion product constant for water (1.0 × 10^-14) and [NH3] is the molar concentration of ammonia.

Therefore, [OH-] = 1.0 × 10^-14/10^(11.30) = 5.0 × 10^-3 M. 
Since [HS-] [H+] / [S^2-] = Kw, we can rearrange this equation to solve for [HS-]: 
[HS-] = Kw /[H+] / [S^2-] = (1.0 × 10^-14 / 10^-11.3) / (10^-14) = 5.0 × 10^-12 M.

Therefore, the answer is (C) 5.0 × 10^-12 M.

An Ammonia Solution Has a PH of 11