Buffer Solutions

Whats a buffer?

resists a change in pH when a small amount of acid or base is added

what is the criteria of a buffer

contain a high concentration of undissociated weak acid and its conjugate base

why doesnt it work with strong acids

they dissociate completely therefore acid concentration is too low

• How do you make a buffer solution?

1. weak acid and a salt of its conjugate base aq or s

2. neutralise a weak acid with a strong base

whats a buffer region

when its the halfway neutralisation point of a weak acid and strong base, its the region that resists a change in pH

How does a buffer region resist a change in pH upon the addition of a small amount of acid

1. write reversible reaction for specific buffer

2. adding the acid increases H+ concentration

3. the equilibrium shifts ti the left lowering H+ concentration

4. H+ concentration roughly remains the same

How does a buffer region resist a change in pH upon the addition of a small amount of base?

• write reversible reaction for specific buffer

• the reaction between H+ and OH- decreases H+ concentration

• the equilibrium shifts to the right lowering H+ concentration

• H+ concentration roughly remains the same

what are the two types of buffers

acidic and alkaline

assumptions we make while calculating a pH of a buffer solution

assume the salt of the weak acid conjugate base is equal to A- and that initial and final mole of weak acid remain the same