Question

a) From the list below, pick an acid, along with its conjugate base, that can be used to make a pH 7.40 buffer.

H3PO4 Ka = 6.9 x 10-3 H2PO4- Ka = 6.4 x 10-8 HPO42- Ka = 4.8 x 10-13

b) If you have 0.100 M solutions of the acid and the conjugate base in the system that you picked and there was 20.0 mL of the base, how many mL of the acid would you need to make this buffer of pH 7.40?

Answer 1

(a) H₂CO₃^- is an acid and HCO₃^2- is a conjugate base

(b) 12.4 mL of the acid is needed to make a buffer with pH = 7.40