Question

Which solution has the highest pH?

A. 0.1 M KClO, Kₐ for HClO is 3.5 x 10⁻⁸
B. 0.1 M of KCl, Kₐ for HCl is VERY LARGE!!
C. 0.1 M of KNO₂, Kₐ for HNO₂ is 4.5 x 10⁻⁴
D. 0.1 M KCH₃COO, Kₐ for CH₃COOH is 1.8 x 10⁻⁵

Answer 1

The solution with 0.1 M KCH₃COO has the highest pH because it is the salt of the weakest acid listed, with a Kₙ of 1.8 x 10⁻⁵, indicating the most basic solution among the choices.

Step-by-step explanation:

To find which solution has the highest pH, we need to determine which one is most basic. Since salts of strong acids and bases do not affect pH, and since KCl and KClO both come from strong bases and their respective weak/strong acids, their solutions will be neutral or slightly basic. KNO₂ and KCH₃COO are salts of weak acids, and they will form basic solutions due to the hydrolysis of their respective anions, NO₂⁻ and CH₃COO⁻. The acid dissociation constant (Kₙ) tells us the strength of the acids: a lower Kₙ indicates a weaker acid, resulting in a more basic solution when the salt is dissolved. Therefore, 0.1 M KCH₃COO, with the weakest parent acid with Kₙ = 1.8 x 10⁻⁵, will form the most basic and thus the highest pH solution among the choices given.