LE CHATELIER's PRINCIPLE

This principle for the factor affecting the balance of chemical equilibrium.Le chatelier principle deacribe the factor which affect the balance of chemical equilibrium.

DEFINITION:
 If a stress is applied on a reaction at equilibrium then reaction changes it's direction reduce the effect of that stress.

EXPLANATION:-
 If a stress is applied on a reaction at equilibrium by changing some factor like concentration , temperature , pressure then it will disturb the balance of chemical equilibrium, and the reaction change it's direction either forward or backward to reduce effect of that stress and acquire equilibrium again.
Effect of diferent factiors on the balance of chemical equilibrium is given below.

1)Effect OF CHANGE IN CONCENTRATION:-
At equilibrium if the concentration of reactants increased then it will disturb the equilibrium and the reaction will take place forward direction to acquire equilibrium again.If the concentration of product is increase then it will also disturb the balance of equilibrium and the reaction will take place in backward direction to acquirw equilibrium again.

2)EFFECT OF CHANGE IN TEMPERATURE:-

i)EFFECT OF CHANGE IN TEMPERATURE ON EXOTHERMIC REACTION:-
In exothermic reaction heat is released in forward direction and absorbe in backward direction.If the temperature is increase then heat will absorb so reaction goes to backward direction. If the temperature is decreased then heat will release so the reaction goes to forward direction.

ii)EFFECT OF CHANGE IN TEMPERATURE ON ENDOTHERMIC REACTION:-
In an endothermic reaction heat absorbed in forward direction and released in backward direction.If temperature is increased then heat will absorb so the reaction goes to forward direction.If the temperature is decreased then the heat will released so the reaction goes to backward direction.

3)EFFECT OF CHANGE IN PRESSURE:-
Pressure effect only gaseous equilibrium.Three types of reactions are affected by pressure.

i) REACTION BY INCREASE OF VOLUME:-
If the pressure is increased then it will disturb the equilibrium and reaction goes to forward direction where volume is decreased.If pressure is decreased then it will also disturb the equilibrium and the reaction goes to forward direction where volume is increased.

ii)REACTION BY DECREASE IN VOLUME:-
If pressure is increase then it will disturb the equilibrium and reaction goes to forward direction where volume is decreased.If the pressure is decreased then it will also disturb the equilibrium and reaction goes to backward direction where volume is increased.

iii)REACTION BY SAME VOLUME:-
Change of pressure has no effect on this equilibrium.

4)EFFECT OF CATALYST:-
Catalyst has no effect on the balance of chemical equilibrium.Catalyst only changes the rate of reaction.

INDUSTRIAL APPLICATION OF LE CHATELIER's PRINCIPLE:-
Important industrial application of Le Chatelier's principle are given below.

1)TO HABBER's PROCESS IN PREPARATION OF NH3 GAS:-
By habber's process NH3 gas is prepared by the reaction:
N2 + 3H2<===>2NH3+46.2kJ/mol
This reaction is exothermic and take place by decrease of volume.
Affect of different factors on it is given below.

i)EFFECT OF CHANGE IN CONCENTRATION:-
At equilibrium if the concentration of reactant N2 and H2 is increased then it will disturb the equilibrium and according to Le Chatelier principle reaction goes to forward direction and gives more product NH3.

ii)EFFECT OF CHANGE IN PRESSURE:-
As the reaction take place by decrease in volume, So if pressure is increased then it will disturb the equilibrium and according to Le Chatelier's principle the reaction take place in forward direction where volume is decreased and give more product NH3.
In order to obtain maximum product reaction take place at 450-500 atm pressure.

iii) EFFECT OF CHANGE IN TEMPERATURE:-
As reaction is exothermic so if the temperature is decreased then according to Le Chatelier's principle heat will be realesed and reaction goes to forward direction and gives more product NH3.
But actually in industry the reaction is carried out at high temperature at 500 degree calcius in presence of iron oxide catalyst which give reduce product but very high rate.

2)TO CONTACT PROCESS IN THE PREPARATION OF SO3 GAS:-
For formation of sulphuric acid by contact process SO3 gas is prepared by reaction:
2SO2+O2<===>2SO3 +395KJ/mol
This reaction is exothermic and take place by decreased in volume.
Affect of different factor on it is below:

i)EFFECT OF CHANGE IN CONCENTRATION:-
At equilibrium if concentration of reactant is increase then it will disturb the equilibrium and according to Le Chatelier's principle the raction goes to forward direction and give more product SO3.

ii)EFFECT OF CHANGE IN PRESSURE:-
As the reaction take place by decrease in volume,So if temperature is increase then it will disturb the equilibrium according to Le Chatelier's principle reaction take place goes to forward direction where volume is decreased and give more product SO3.
In order to obtain maximum product reaction should be take place at 450-500 atm pressure.

iii)EFFECT OF CHANGE IN TEMPERATURE:-
As the reaction is exothermic so if the temperature is decreased then according to Le Chatelier's principle heat will be released and reaction take place goes to forward direction and gives more product SO3.
But actually in industry the reaction is carried out at high temperature up to 500 degree calcius in the presence of vanadium penta oxide catalyst which gives reduce product but at very high rate.