A solution is prepared by dissolving 0.23 mol of nitrous acid and 0.27 mol of sodium nitrite 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 K_a of nitrous acid is 1.36 × 10^-3. A) H₂O B) H₃O⁺ C) nitrite ion D) nitrous acid E) This is a buffer solution: the pH does not change upon addition of acid or base.

Question

Quizplus · Accepted Answer

The HCl reacts with the nitrite ion (NO2-) present in the buffer solution. In a buffer system composed of a weak acid (nitrous acid, HNO2) and its conjugate base (nitrite ion, NO2-), the addition of a strong acid like HCl will lead to the reaction of HCl with the conjugate base (NO2-) to form more of the weak acid (HNO2), thus preventing a drastic change in pH.

A Solution Is Prepared by Dissolving 0