I need help with le chateliers principle. Watch
It involves reversible reactions (where it can proceed in the forward or reverse direction).
Let's say, for example, you have 2 moles of reactant and one mole of product:
[R](g) + [R](g) <--> [P](g)
If you were to increase the pressure of the system (decrease in volume) the reaction would proceed in the FORWARD direction, increasing the yield of the products; effectively, counterbalancing any changes imposed on the system.
The same applies in the reverse.
That's just one example involving a change in pressure, but it applies for changes in concentration too.
The underlying principle is that the system will favour whichever direction that will result in the LEAST amount of change.
Increasing pressure causes the equilibrium to move to the side of fewest molecules
Increasing temperature causes the equilibrium to move to the side of the endothermic reaction
Increasing concentration of the products will move the equilibrium to the side of the reactants
And vice versa
To visualize and to show the utility of this principle I will name an example for you.
On the left side of the chemical equilibrium there is sulfur dioxide and on the right one, there is Dinitrogen tetroxide plus heat.
2 NO2 <> N2O4 + heat
As you can see its an equilibrium, two nitrogen atoms and four oxygen atoms on both sides. If the temperature is increased, heat is spent, the equilibrium changes to the left side. The yield of nitrogen dioxide (NO2) is increased.
In the other way round when the temperature is decreased, the equilibrium changes to the right side, the yield of dinitrogen tetroxide (N2O4) increases and heat is released.
You see? thanks to the principle of le chetalier, the amount of chemical substances can be regulated in an equilibrium.