Enough of a monoprotic acid is dissolved in water to produce a 0.0169 M solution. The pH of the resulting solution is 2.68. Calculate the Ka for the acid.

Answer 1

Convert pH 2.68 to (H^+) with
pH = -log(H^+).
Then HA --> H^+ + A^-
Ka = (H^+)(A^-)/(HA)
Substitute for (H^+) and (A^-). For (HA) substitute 0.0169-(H^+)