By Team Aakash Byju's | 17th December 2022

Hydrolysis of Salts and the pH of Their Solutions

A

6.02

pK   of acetic acid and pK   of ammonium hydroxide are 4.76 and 4.75 respectively. Calculate the pH of the ammonium acetate solution.

a

b

B

7.005

C

8

D

5.602

Detailed Explanation

The correct answer is  B) 7.005.

Arrow

Given the pK   of acetic acid (CH  COOH) =4.76 and  pK   of ammonium hydroxide  (NH   OH) = 4.75.

a

3

4

b

Ammonium acetate (CH COONH ) is a salt of a weak acid, acetic acid (CH COOH), and a weak base ammonium hydroxide (NH OH).

Step 1: Salt type

3

4

3

4

The reaction taking place is:

CH COOH + NH OH

CH COONH + H O

3

3

4

4

2

Step 2: Formula of pH

For salt of a weak acid and weak base, the pH of salt in solution is given as:

a

b

pH=7+1  [pK –pK  ].

2

Step 3: pH value

pH=7+    [0.01]

a

b

pH=7+    [pK –pK  ]

2

2

pH=7.005.

pH=7+0.005

=>

1

1