Q. Show the Effect of concentration on Chemical Equilibrium?

Ans.

When more of one of the chemicals is added to the reaction, more collisions take place moving the reaction to the opposite side. Some of the added chemicals react to form the products. In other words, according to Le Chtelier's Principle, something has occurred to minimize the change.

Consider the following equilibrium reaction:

A + B -> C + D

If the product C is removed by liquefaction or escaping into the atmosphere, etc., the reverse reaction cannot occur. The position of the equilibrium is said to move to the right, or towards the products.

However, if the reactant A is removed, the forward reaction can not occur. Therefore, the position of the equilibrium moves to the left, towards the reactants. Use Le Chtelier's Principle to explain why increasing the amount of C will shift the equilibrium to the left, and why increasing the amount of A will shift the equilibrium to the right.

For example, consider the following equilibrium reaction:

H₂ (g) + I₂(g) -> 2HI(g)

If additional H₂ is added to the reaction, the change will be minimized by an increase in the production of HI. However, if more HI is added to the reaction, the equilibrium will be restored with an increase in the formation of H₂ and I₂.

The following animation illustrates the effect of acidity on equilibrium position:

When the yellow chromate solution is treated with hydrochloric acid, it changes to an orange dichromate solution. When the orange dichromate solution is treated with sodium hydroxide (a strong base), it returns to the chromate solution with the yellow color.