# How do buffers maintain pH?

##### 2 Answers

Buffers moderate both

#### Explanation:

The weak acid

As with any equilibrium, we can write the equilibrium expression:

This is a mathematical expression, which we can divide, multiply, or otherwise manipulate PROVIDED that we do it to both sides of the expression. Something we can do is to take

(Why? Because

Rearranging,

But BY DEFINITION,

, and

Thus

Do not be intimidated by the

Given our equation, it tells us that when

Buffers thus moderate

I acknowledge that I have hit you with a lot of facts. But back in the day A level students routinely used log tables before the advent of electronic calculators. If you can get your head round the logarithmic function you will get it.

Buffers react with added acid or base to resist a change in pH.

#### Explanation:

Buffers are special solutions that react with added acid or base to limit the change in pH levels.

For instance, carbonic acid is a weak acid that does not dissociate completely while in water - a small amount is dissociated into

#"H"_2"CO"_3 ⇌ "H"^"+" + "HCO"_3^"-"#

If you add

If you add