Question

What is a buffer solution and how does it work?

Answer 1

A buffer solution is comprised of a weak acid and its conjugate base, such that,

`HA rightleftharpoons A^(-) + H^(+)`

It's very apparent when evaluating a titration curve,

In the buffering region, the rate of `"pH"` increase as a function of hydroxide addition is relatively less than outside of the buffering region.

Two equilibria are coexisting, and when one transiently exceeds its equilibrium constant, it readjusts and affects the other equilibrium, that further adjusts.

Hence, the function of a buffer is to stabilize the `"pH"` of a solution against the addition of other acids or bases.

A notable example is the bicarbonate buffer system in your blood plasma,

`H_2CO_3 rightleftharpoons HCO_3^(-) + H^(+)`

where `H_2CO_3` is derived from dissolved `CO_2` in your capillaries (which is originally from your lungs).

Enzymes function at characteristic optimal `"pH"`, and the blood plasma's buffer system ensures blood is between `7.35` and `7.45`.