A volume of 50.00 mL of a weak acid of unknown concentration is titrated with 0.10 M solution of NaOH. The equivalence point is reached after 39.30 mL of NaOH solution has been added. At the half-equivalence point (19.65 mL), the pH is 4.85. Thus, initial concentrations of the acid and its values are
When half-equivalence point is reached