What is the buffer component ratio, (BrO-)/(HBrO) of a bromate buffer that has a pH of 9. Ka of HBrO is 2.3 x 10-9.

Question

What is the buffer component ratio, (BrO^-)/(HBrO) of a bromate buffer that has a pH of 9. K_a of HBrO is 2.3 x 10^-9.

the answer is 2.29

Answer 1

Henderson Hasselbalch equation:

pH = pKa + log [salt]/[acid]

pKa = -log 2.3x10^-9 = 8.638

9 = 8.638 + log [salt]/[acid]

log [salt]/[acid] = 0.362

Taking the antilog of 0.362 you get [salt]/[acid]...

[salt]/[acid] = 2.3 (the answer of 2.29 has 3 significant figures which seems to be 1 too many)