Question

73. The pH of an aqueous solution of 1.5 M of
ammonium acetate is (Given : pk, of CH3COOH
and pKo of NH OH both are equal to 4.74 at 25°C)
(1) 7
(2) 6
(3) 9.45
(4) 9​

Answer 1

Ammonium formate is a salt of weak acid and weak base. Hence, we apply the formula,

pK

a

=3.8, pK

b

=4.8

pH=7+

2

1

pK

a

−

2

1

pK

b

=7+(1/2)×3.8−(1/2)×4.8=7+1.9−2.4=6.5