Answer:
(I) Decrease in temperature from 500oC to 100oC will increase the rate of the forward reaction.
(II) Decreasing the concentration of nitrogen will decrease the reaction rate of the forward reaction.
(III) Increasing the concentration of ammonia will increase the rate of the reverse reaction.
(IV) When a catalyst is added, the rate of the forward reaction increases while that of the reverse reaction decreases.
Explanation:
Chemical equilibrium is a dynamic reversible process where both the forward and reverse reactions occur at the same time and the concentration of all the chemical species in the system remain constant under standard conditions. Equilibrium state is dependent on:
I. Temperature of the reacting system.
II. Concentration of the reacting system.
III. Pressure of the reacting system ( for gases ).
The reaction equation for the Haber process of ammonia production: N2(g) + 3H2(g) <-> 2NH3(g)
According to Le Chatelier's principle that if an external stress or factor is imposed on an equilibrium system, the equilibrium shifts to annul or neutralize the stress:
(I) Decrease in temperature from 500oC to 100oC will increase the rate of the forward reaction because it was originally in the equilibrium state of a higher temperature.
(II) Decreasing the concentration of nitrogen will decrease the reaction rate of the forward reaction by decreasing the formation of ammonia (product).
(III) Increasing the concentration of ammonia will increase the rate of the reverse reaction by preventing its formation from the reactants nitrogen and hydrogen.
(IV) When a catalyst is added, the rate of the forward reaction increases while that of the reverse reaction decreases. This is achieved by the catalyst lowering the activation energy ( the minimum energy required for the reaction to occur ) of the reaction, hence, making it to occur faster.
