Question

A salt containing a common ion is added, the equilibrium shifts in the backward direction. This phenomenon is called​

Answer 1

This phenomenon is called common ion effect.

• The common ion effect can be described as a phenomenon that mentions the change in equilibrium when an ion that is already present in the solution, i.e. a common ion is added to the solution.
• For example: Addition of NaCl in a solution of HCl and water.
• It is widely used to make an ion completely precipitate from the solution.

Answer 2

This phenomenon is called COMMON ION EFFECT .

Let me explain in easy terms !

• First of all, consider a chemical equilibrium equation as follows:

$NH_{3} + H_{2}O\iff NH_{4}^{+} + OH^{-}$

• So, in the above reactions the various ions produced are ammonium ion and hydroxyl ion.

• Now, let's say, we add another fully ionisable compound as follows:

$NH_{3} + H_{2}O\iff NH_{4}^{+} + OH^{-}$

$NH_{4}Cl \rightarrow NH_{4}^{+} +Cl^{-}$

• Here ammonium ion becomes the common ion, it's concentration increases.

• This increase in the concentration of the common ion in the product side will push the equilibrium reaction backwards towards the reactant side.

THIS IS CALLED COMMON ION EFFECT !