Question

Enough of a monoprotic acid is dissolved in water to produce a 0.0142 M solution. The pH of the resulting solution is 2.58. Calculate the Ka for the acid.

Answer 1

Ka = 4.9 x 10ˉ⁴

Step-by-step explanation:

HOAc ⇄ H⁺ + OAcˉ

Ka = [H⁺][OAcˉ]/[HOAc]

Given pH = 2.58 => [H⁺] = [OAcˉ] = 10ˉ²∙⁵⁸ = 2.63 x 10ˉ³M

Ka = (2.63 x 10ˉ³)²/(0.0142) = 4.9 x 10ˉ⁴