Formula For Salts of Strong Acids and Weak Bases

Formula For Salts of Strong Acids and Weak Bases

Sep 06, 2022, 16:45 IST

Salts of strong acids and weak bases [SA-SB]

Such salts give acidic solutions in water. Some of such salts are : NH ₄ Cl, ZnCl ₂ , FeCl ₃ etc. For the purpose of discussion, we will consider hydrolysis of NH ₄ Cl. For More C hemistry Formulas just check out main pahe of Chemsitry Formulas.

When NH ₄ Cl is put in water, it completely ionises in water to give NH ₄ ⁺ and Cl ^- ions. NH ₄ ⁺ ions combine with OH ^- ions furnished by weakly dissociated water to form NH ₄ OH (weak base). Now for keeping K _w constant, water further ionises to give H ⁺ and OH ^- ions, where OH ^- ions are consumed by NH ₄ ⁺ ions leaving behind H ⁺ ions in solution to give an acidic solution.

pH of solution :

Example For Salts of Strong Acids and Weak Bases

Example 1

The basic ionisation constant for hydrazine, N ₂ H ₄ is 9.6× 10 ^–7 . What would be the percent hydrolysis of 0.1 N ₂ H ₅ Cl ?

A. 0.016
B. 3.2
C. 1.6
D. 0.032

Ans. D

Example 2

The pH of a 0.02 M aqueous solution of NH ₄ Cl  is equal to

A. 3.78
B. 4.73
C. 5.48
D. 7.00

Ans. A