Acids, Bases, Buffers, and Titration – General Chemistry Study Guide

A solution is prepared by combining approximately equal amounts of carbonic acid and sodium bicarbonate in water. The addition of a small amount of HCl to this buffer solution causes the pH to rise slightly. The pH does not increase drastically because the HCl reacts with the ________ present in the buffer solution.

Calculate the pH of a solution that is 0.38 M in carbonic acid ($\mathrm{H_2CO_3}$) and 0.18 M in sodium bicarbonate ($\mathrm{NaHCO_3}$). The $K_a$ of carbonic acid is $4.3 \times 10^{-7}$.

What is the approximate pH at the equivalence point of a weak acid–strong base titration if 25 mL of aqueous acetic acid requires 35 mL of 0.12 M NaOH to reach the equivalence point? $K_a = 1.8 \times 10^{-5}$ for acetic acid.