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Wednesday, 23 December 2015

FSc Notes Chemistry Part 1 Chapter 8 Chemical Equilibrium Lecture 7

FSc Notes Chemistry Part 1 Chapter 8 Chemical Equilibrium Lecture 7



Buffer Action:

The ability of a buffer to resist change in its PH, even after the addition of small amount of strong acid or base is known as buffer action.
Now the question arises that how a buffer solution resists change in its PH, even with the addition of small amount of a strong acid or base.
It can be explained as: consider the CH3COOH / CH3COOna solution: if we acid small amount of a strong acid like HCL the PH doesn’t change. It is between of the fact that in CH3COOH / CH3COONa : CH3 COOH ionizes to large extent : so there are CH3COO- in large excess which come from CH3COONa . Here common ion effect of CH3COOH and HCL occurs because both produce H+. As a result the solubility of CH3COOH is further decreased. Thus most of H+ ion of HCL ( which are responsible for change of PH ) are converted into in weak acid, CH3COOH which is already in excess In buffer solution.
Thus the PH of buffer remains constant because H+ ions of HCL don’t remain in solution.

Buffer Capacity:

The extent till which a buffer can resist change in its PH is known as buffer capacity. A buffer can resist change in its Ph if we add particular amount of strong acid or base. If we exceed the amount of strong acid or base them the ph of ph will certainly change. So we can say  that there is certain limit till which a buffer can resist change in its ph. This limit is known as buffer  as buffer capacity.

Calculation of PH of Buffer Solution:

The ph of a buffer solution is calculated by an equation known as "Hander son Herelback equation" This equation is
Ph = Pka + log [ base ]-------------[acid ]

Application of Buffer Solutions:

  1. Buffer solutions have tremendous applications. Some important applications of Buffer Solutions are .The human blood is a buffer whose then serious problems may happen. In spite of having so many acidic and basic substances: the ph doesn’t changes.
  2. Buffer solutions are mostly used in Analytical laboratories for carrying out particular reactions at particular ph.
  3. Buffer solutions are used are used in various industries.
  4. Buffer solutions are used in Biological laboratories etc.

Written by: Asad Hussain

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