Question

How does a buffer solution resist change in ph?

Answer 1

A buffer is essentially a weak acid + its conjugate

for example

Acetic Acid, let it be HA where H+ is the prton and A- is the acetate ion

then

HA <--> H+ and A- in solution

if we add NaA (sodium acetate) then we will have

NaA ---> Na+ and A-

there is common ion effect, which is the conjugate "A-"

as we add acid; we form more HA

as we add base, we form more A-

therefore, the equilibrium is shifted depending on which side

note that buffers have certain capacity until pH changes drastically