Buffer Solutions:-

Buffer is a substance which resist the change in its pH value. Even when small amount of acid or base are added to it.

Type of buffer:-

• Solution of single substance:- The solution of a salt of weak acid & weak base.

For example:- CH3COO^-NH₄⁺ act as a buffer

• Solution of mixture:-  There are of two types:

1. Acidic buffer:- It is a solution of a mixture of weak and al salt of this weak acid with a strong base.

e.g. :- CH₃COOH + CH₃COO Na

2. Basic buffer:- It is the solution of a mixture of weak base & a salt of this weak base with a strong acid.

NH₄OH + NH₄Cl

Buffer action:- The property of a buffer solution to resist any change in its pH value even when small amount of acid or base are added to it is called to it is called buffer action.

CH₃COO^- + H⁺ ⟶ CH₃COOH

NH₄⁺ + Cl^- ⟶ NH₄Cl

NH₄⁺ + OH^- ⟶ NH₄OH

Buffer action of acidic Buffer

Acidic Buffer:- CH₃COOH + CH₃COO Na

 

CH₃ – COONa ⟶ CH₃COO^- + Na⁺

HCl ⟶ H⁺ + Cl^-

CH₃COO^- + H⁺ ⟶ CH₃COOH

2^nd case

NaOH ⟶ Na⁺ + OH^-

H⁺ + OH_- ⟶ H₂O

Excess of CH₃ COO^- & Na+ form CH₃ COO Na

Buffer action of basic buffer:

Basic Buffer:- NH₄OH + NH₄Cl

NH₄ Cl ⟶ NH₄⁺ + Cl^-

Let HCl ⟶ H⁺ + Cl^-

H⁺ + OH^- ⟶ H₂O

NaOH ⟶ Na⁺ + OH^-

NH₄⁺ + OH^- ⟶ NH₄OH