A solution is prepared by dissolving 0.23 mol of formic acid and 0.27 mol of sodium formate in water sufficient to yield 1.00 L of solution. The addition of 0.05 mol of HCl to this buffer solution causes the pH to drop slightly. The pH does not decrease drastically because the HCl reacts with the ________ present in the buffer solution. The of formic acid is 1.36 × 10^-3. A) O C) formate ion D) formic acid E) This is a buffer solution: the pH does not change at all upon addition of acid or base.

Question

Quizplus · Accepted Answer

The purpose of a buffer solution is to resist changes in pH upon addition of acid or base. In this case, formic acid and sodium formate are used as a buffer. When HCl is added, it reacts with the formate ion (CHO2-) to form formic acid (HCHO2), which is a weak acid with a low dissociation constant. This reaction helps to neutralize the added HCl and prevent a drastic drop in pH. Therefore, the correct answer is C, formate ion.

A Solution Is Prepared by Dissolving 0