Buffer solutions

High School

Definition

A solution that resists changes in pH when small amounts of acid or base are added. Buffers usually contain a weak acid and its conjugate base, and they are important in keeping the pH of blood and other systems stable.

Worked examples

An acetic acid/acetate buffer: \(\)CH\(_3\)COOH\(\) and \(\)CH\(_3\)COO\(^-\) keep pH near 4.76

The weak acid and its conjugate base pair resist pH changes when small amounts of acid or base are added.

Adding \(\)H\(^+\): \(\)CH\(_3\)COO\(^- + \)H\(^+ \)→\( \)CH\(_3\)COOH\(\)

The conjugate base neutralizes added acid, preventing a large pH drop.

Adding \(\)OH\(^-\): \(\)CH\(_3\)COOH\( + \)OH\(^- \)→\( \)CH\(_3\)COO\(^- + \)H\(_2\)O\(\)

The weak acid neutralizes added base, preventing a large pH rise.

Common mistakes

A buffer is made from any acid and any base mixed together → A buffer requires a weak acid and its conjugate base (or weak base and its conjugate acid) Strong acids/bases dissociate completely and cannot maintain equilibrium to resist pH changes.
Buffers can resist unlimited amounts of added acid or base → Buffers resist only small amounts; they have a limited buffering capacity Once the weak acid or conjugate base is used up, the buffer is overwhelmed and pH changes sharply.
Buffer pH stays exactly constant no matter what → Buffer pH changes slightly but resists large swings Buffers minimize pH change but don't eliminate it entirely when acid or base is added.

Where you'll use it next

You'll use buffer solutions in acid-base equilibrium calculations, titration curve analysis, and biochemistry when studying enzyme function and blood pH regulation (bicarbonate buffer system).

Found in 1 StudyPug lesson

Understanding Buffer Solutions: Composition and Function

A-Level Chemistry

Explore the world of buffer solutions! Learn what makes a buffer, how it maintains pH stability, and its crucial role in chemistry and biology. Master buffer equations and real-world applications.

12th Grade12th