Determine whether or not adding 0.020 mol of naoh exceed the capacity of the buffer.

A buffer solution is a solution whose pH does not vary or little when adding an acid or a base, or during a dilution.

The buffering capacity is the number of moles of acid or strong base to add to 1 L of buffer solution to vary the pH of one unit.

So if we add 0.020 mol of NaOH this will vary the dpH depending on the buffer capacity of the solution.

We Have : Cacid (AH) = 0.1mol/l

Cbase (A-) = 0.2mol/l

The reaction of the buffer with NaOH will be:

AH + NaOH = A - + Na + H2O

t0 0.1mol 0.02mol 0.2mol

t1 0.08mol 0 0.22mol

At the end of the reaction we will have:

Concentration of acid = 0.08mol/l

Concentration of the conjugate = 0.22mol/l

So the capacity of the buffer will not be exceed, it still remains both parts of the buffer