For a system to be in chemical equilibrium, the speed of direct reaction must be equal to the speed of inverse reaction.
The conditions surrounding these reactions should not be changed. If this occurs, there will be a change in balance. These modifications can be:
- concentration of reagents and products
- presence of catalyst
These modifications may benefit the reaction in one direction (direct or reverse). We call these disturbances balance shift.
Balance shift - Any change in the speed of direct reaction or reverse reaction, causing changes in the concentrations of substances and leading the system to a new state of chemical equilibrium.
When the speed of reaction straightforward increases is because the balance is shifting to the right.
When the speed of reaction inverse increases is because the balance is shifting to the left.
The study of equilibrium displacements was developed by the French chemist. Le chatelier.
It is possible to predict what happens to the reaction according to the change that is made. Le Chatelier's statement says:
“When an external factor acts on an equilibrium system, it moves, trying to minimize the action of the applied factor.”
Influence of concentration
An increase in either concentration results in an equilibrium shift to the other side. The removal of some substance causes the displacement to its side.
During modifications, the values of all concentrations change, but the KC value remains the same.
If the reagent concentration increases, the reaction needs to produce more product, so it shifts to the right.
If the reagent concentration decreases, the reaction needs to produce more of the reagent itself, so it shifts to the left.
If the product concentration increases, the reaction needs to produce more reagent, so it shifts to the left.
If the product concentration decreases, the reaction needs to produce more of the product itself, so it shifts to the right.