A 200.0 mL sample of 0.18 M HClO₄ is titrated with 0.36 M NaOH.Determine the pH of the solution before the addition of any NaOH. A) 1.74 B) 1.05 C) 0.74 D) 0.57 E) 1.57

Question

Quizplus · Accepted Answer

HClO is a weak acid while NaOH is a strong base. Therefore, at the beginning of the titration, the solution contains a weak acid and its conjugate base. The pH can be calculated using the Henderson-Hasselbalch equation:

pH = pKa + log([ClO-]/[HClO])

The pKa of HClO is 7.53, and at the beginning of the titration, the concentration of HClO is 0.18 M while the concentration of ClO- (from the dissociation of HClO) is 0. The pH can be simplified to:

pH = 7.53 + log(0/0.18) = 0.74

Therefore, the pH of the solution before the addition of any NaOH is 0.74.

A 2000 ML Sample of 0