8.5 Buffers

What does buffer capacity depend on?

The concentration of the acid/conjugate base (or the base/conjugate acid) in the buffer solution

When has the buffer capacity reached its maximum?

When the ratio of the concentration of the buffer components is close to 1.

Give an example of buffers in the human body.

pH of human blood plasma is about 7.4; if the pH of the blood changes more than 0.2, it is life threatening; blood plasma has a remarkable buffering capacity

What is more resistant to change?

A concentrated buffer resists changes more than a diluted buffer.

Define buffer.

A solution that contains a weak acid/conjugate base mixture or a weak base/conjugate acid mixture; it resists change in pH when a moderate amount of an acid or a base is added to it

Define buffer capacity.

Amount of an acid or base that can be added before considerable change occurs to the pH.

How are buffers made? Give examples.

By using a weak acid and one of its salts; for example, by mixing acetic acid + sodium acetate. By using a weak base and one of its salts; for example, by mixing ammonia and ammonium chloride.

Where are buffers also used?

In many consumer, commercial and industrial applications

Explain a buffer solution using acetic acid and sodium acetate.

[CH3COOH] and [CH3COO-] are both high; adding an acid or a base has little effect because the added H3O+ or OH- ions are removed by one of the components in the buffer solution; equilibrium shifts as predicted by Le Chatelier's Principle