Predict whether the equilibria
I) CO2(g) + 2 NH3(g) =
CO(NH2)2(s) + H2O(g),
AH° = -90 kJ
II) Ni(s) + 4 CO(g) = Ni(CO)4(8),
AH° = -161 kJ
will shift toward products or reactants with a
temperature increase.
1. I shifts toward reactants and II shifts
toward products.
2. Both I and II shift toward products.
3. Unable to determine
4. Both I and II shift toward reactants.
5. I shifts toward products and II shifts to-
ward reactants.

This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.

For exothermic reaction :ΔH = negative

If the temperature is increased, so according to the Le-Chatlier's principle , the equilibrium will shift in the direction where decrease in temperature occurs.So, equilibrium will move in backward direction.
If the temperature is decreased , so according to the Le-Chatlier's principle , the equilibrium will shift in the direction where increase in temperature occurs.So, equilibrium will move in forward direction.

For the given equation:

I) [tex]CO_2(g) + 2 NH_3(g) \leftrightharpoons CO(NH_2)_2(s) + H_2O(g)[/tex] ,ΔH° = -90 kJ

On Increasing the temperature

This is an exothermic reaction, backward reaction will decrease the temperature. Hence, the equilibrium will shift in the left direction that is towards reactants.

II) [tex]Ni(s) + 4 CO(g)\leftrightharpoons Ni(CO)4(g)[/tex] ,ΔH° = -161 kJ

On Increasing the temperature

This is an exothermic reaction, backward reaction will decrease the temperature. Hence, the equilibrium will shift in the left direction that is towards reactants.