21 Buffers and Neutralisation

buffer def

a solution that resists change to pH upon addition of small amounts of H+ and OH-

(the pH does change but only slightly)

how are buffers made

from a weak acid and the salt of a weak acid

(or weak base/salt of a weak base)

Ka formula

what affects Ka

only temperature

henderson hasselbalch equation

when HA : A- is 1:1, what’s the relationship between pH and pKa?

pH=pKa

indicator def

a weak acid where HA and A- have different colours

equivalence point def

the point at which the moles of acid = moles of base

end point def

the point at which the indicator will change colour

how do we choose an indicator

choose one that changes colour at the equivalence point

what is the pH of the equivalence point also = to

the pH of the salt formed