Answer is: the
equilibrium concentration of benzoic acid is 0,06294 M.
Chemical reaction: C₆H₅COOH(aq) ⇄ H⁺(aq) + C₆H₅COO⁻<span>(aq).
Ka(C</span>₆H₅COOH) = 6,3·10⁻⁵.
c(C₆H₅COOH) = 6,3·10⁻² M.
[H⁺] = [C₆H₅COO⁻<span>] = x; equilibrium
concentration.
[C</span>₆H₅<span>COOH] = 0,063 M - x.
Ka = [H</span>⁺] · [C₆H₅COO⁻] / [C₆H₅<span>COOH].
0,000063 = x² / 0,063 M - x.
Solve quadratic equation: x = 0,00006 M.
[C</span>₆H₅COOH] = 0,063 M
- 0,00006 M.<span>
[C</span>₆H₅<span>COOH] = 0,06294 M</span>
