Finding pH of 0.215M HCIO2

Question

Please find the pH of 0.215M HCIO₂(aq) solution. Ka=0.011

Answer 1

HClO₂ <==> H⁺ + ClO₂^- ... Ka = 0.011

Ka = [H⁺][ClO₂^-] / [HClO₂]

0.011 = (x)(x) / 0.215 - x

x² = 0.002365 - 0.011x

x² + 0.011x - 0.002365 = 0

x = 0.0434 M = [H⁺]

pH = -log [H⁺]

pH = -log 0.0434

pH = 1.36