Buffer Solutions

Buffer solution

a solution containing a weak acid and its conjugate base or a weak base and its conjugate acid

can resist a change in pH

Does HCl and NaOH create a buffer

no because there is no conjugate acid-base pair, HCl is a strong acid and NaOH is a strong base therefore both ionize completely

Common ion effect

a phenomenon where the addition of a strong electrolyte containing a common ion suppresses the ionization of a weak electrolyte

Do strong acids and bases create a buffer solution

no because it completely ionizes

What is the Henderson-Hasselbalch equation used for

calculate pH of a buffer with specific concentrations of acid and conjugate base, or base and conjugate acid

How does a buffer keep its pH constant when we try to change its pH by adding strong acid or base

When strong acid is added, the H+ ions from the strong acid reacts with the conjugate base present in the buffer solution

When strong base is added, OH- ions from the strong base react with the weak acid in the buffer solution

Buffer capacity

the ability of a buffer solution to resist a change in pH when an acid or base is added

a buffer that has a higher concentration of conjugate acid and conjugate base will have a stronger resistance

Two factors of buffer capacity

concentration of acid/base and conjugate base/acid (higher concentration = higher strength), ratio of the conjugate over acid/base (ration closer to 1 = higher the capacity)

Conditions to make the best buffer

• concentrations of weak acid/base have to be high

• ratio of the conjugate over weak acid/base should be close to 1

• pH desired should be close to pKa