A buffer solution is prepared by mixing 1.00 L of 0.050 M pentafluorobenzoic acid (C6F5COOH) and 1.00 L of 0.060 M sodium pentafluorobenzoate (NaC6F5COO). The Ka of this weak acid is 0.033. Determine the pH of the buffer solution.

pH = 1.401

Explanation:

Using The Henderson-Hasselbalch Equation

pH = pKa + log [base] / [acid]

Ka = 0.033

pKa = - log Ka

pKa = - log 0.033

pKa = 1.48

[base] = concentration of congugate base = 0.060 M

[acid] = concentration of Acid = 0.050 M

pH = pKa + log ([base] / [acid])

pH = 1.48 + log (0.050 / 0.060)

pH = 1.48 + log 0.83

pH = 1.48 - 0.079

pH = 1.401

the pH of the buffer solution is 1.401