Prepare a Buffer by Combining a Solution of Weak Acid with a...

Prepare a Buffer by Combining a Solution of Weak Acid with a Solution of the Salt of the Weak Acid Given 0.1 $M$ solutions of acetic acid and sodium acetate, describe the preparation of 1 L of 0.1 M acetate buffer at a pH of 5.4.

Key Concepts

Buffer Solutions

A buffer solution is composed of a weak acid and its conjugate base (or a weak base and its conjugate acid) that work together to resist changes in pH when small amounts of strong acid or base are added. This stability is due to the equilibrium between the acid and its conjugate base, which can absorb added hydrogen or hydroxide ions, thereby maintaining the overall pH of the solution.

Henderson-Hasselbalch Equation

The Henderson-Hasselbalch equation provides a useful way to relate the pH of a buffer solution to the pKa of the weak acid and the ratio of the concentrations of the conjugate base to the acid. It is an essential tool for designing buffers with a desired pH, as it allows one to calculate the required proportion of acid and conjugate base in the mixture.

Weak Acids and Conjugate Bases

Weak acids only partially ionize in solution, resulting in a dynamic equilibrium between the acid and its conjugate base. This equilibrium is a key feature in buffer systems, where the weak acid (and its corresponding salt providing the conjugate base) works together to neutralize any added strong acids or bases, thereby helping to maintain a steady pH.

Buffer Preparation and Dilution

Preparing a buffer involves accurately mixing solutions of a weak acid and its conjugate base in calculated proportions to achieve a specific pH and ionic strength. The process usually requires the use of the Henderson-Hasselbalch equation to determine the correct ratio of the acid to its conjugate base, followed by careful dilution to obtain the final desired volume and concentration.

Transcript

Please give Ace some feedback