A 25.0 mL sample of 0.723 M HClO₄ is titrated with a 0.273 M KOH solution. The H₃O⁺ concentration after the addition of 0.00 mL of KOH is ________ M. A)0.0181 B)0.430 C)0.723 D)0.273 E)none of the above

Question

Quizplus · Accepted Answer

At the beginning of the titration, no KOH has been added, so the concentration of HClO is still 0.723 M. The concentration of H+ is also 0.723 M, since HClO is a strong acid and dissociates completely. Therefore, the [H+] = 0.723 M. The pH can be calculated as follows:
pH = -log[H+]
pH = -log(0.723)
pH = 0.14
Since HClO is a weak acid, the pH will be slightly less acidic than what would be expected for a strong acid of the same concentration. However, this effect is negligible in this case. The concentration of HSO+ after the addition of 0 mL of KOH is equal to the concentration of HClO, which is 0.723 M.

A 250 ML Sample of 0