Question

If the buffer consisted of 75% acetic acid and 25% acetate , would the buffer capacity be the same for both HCl and NAOH titrations? Explain how you would expect it to differ.

Answer 1

NO . The buffer capacity is not same for HCl and NaOH titrations.

Let us assume total number of moles in buffer are 1.0

a) with HCl

HA ---------------------> A- + H+

0.75 0.25 0

To exhaust the buffer capacity moles of H+ needed are 0.25

then

1.00 0 0

b) If NaOH is added

HA + OH- ----------------> A- + H2O

0.75 0 0.25 initial moles

To exhuast the buffer , we need to add 0.75 moles of base.

0 0 1.00

Thus the buffer capacity is not same with HCl and NaOH with the given buffer.