General Chemistry 2

Question

What is the pH of a buffer made from 0.350 mol of HBrO (Ka = 2.5 × 10⁻⁹) and 0.100 mol of KBrO in 2.0 L of solution?

Answer 1

pKa = -log Ka = -log 2.5x10^-9 = 8.60

Henderson Hasselbalch equation:

pH = pKa + log [conj.base]/[acid]

[conj.base] = 0.100 mol/2.0 L = 0.0500 M

[acid] = 0.350 mol/2.0 L = 0.175 M

pH = 8.60 + log 0.050/0.175

pH = 8.60 + log 0.286

pH = 8.60 -0.544

pH = 8.06