Help - Equilibrium Law & the Strength of Acids and Bases

Question

BASE Question:

The pH of a solution of 4.58 mol/L acetic acid in water is a.bc

Answer 1

First, you didn't provide any options for a, b or c. Second, in order to answer a question like this, and the others that you've posted, you need to know the Ka of the acid or Kb of the base. In this case, the Ka for acetic acid is 1.8x10^-5, which is the value I'll use.

Acetic acid is a weak acid and can be represented as HA.

HA ==> H⁺ + A^-

Ka = 1.8x10^-5 = [H⁺][A^-]/[HA] = (x)(x) / 4.58

x² = 8.24x10^-5

x = [H⁺] = 9.1x10^-3 M

pH = -log [H⁺] = -log 9.1x10^-3

pH = 2.0

NOTE: You can do all the other problems you've posted on the same subject by the same method.