Equilibrium

Equilibrium

Question

pKa of a weak acid (HA) and pKb of a weak base (BOH) are 3.2 and 3.4, respectively. The pH of their salt (AB) solution is

  • 7.2

  • 6.9

  • 7.0

  • 1.0

Answer

B.

6.9

Given
pKa (HA) = 3.2
pKb (BOH) = 3.4
As given salt is of weak acid and weak base
therefore,
pH = 7 + (1/2)pKa - (1/2)pKb
= 7 + (1/2)(3.2) - (1/2)(3.4)
= 6.9

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