Answer
See explanation below.
Work Step by Step
1
Formula :
1. The Henderson - Hasselbalch equation of a buffer is as follows :
pH = pKa + log [conjugate base] / [acid]
2. pKa = -log(Ka)
2
Solution :
Here,
1. pH = 7.40 ........ (given)
2. Ka = 6.3 x 10^-8 ..... (from Appendix C)
So,
pKa = -log(Ka)
= -log(6.3 x 10^-8)
= 7.20
3.
pH = pKa + log ([KH2PO4] / [Na2HPO4])
7.40 = 7.20 + log (([KH2PO4] / [Na2HPO4]))
log (([KH2PO4] / [Na2HPO4])) = 0.20
[KH2PO4] / [Na2HPO4] = Antilog (0.20)
= 1.584
Hence, the buffer component ratio is equal to 1.584
