Question

For the given reaction at equilibrium,
$2S{O_2}{\text{(g) + }}{{\text{O}}_2}{\text{(g) }} \rightleftharpoons {\text{ 2S}}{{\text{O}}_3}{\text{(g) + 189}}{\text{.4 kJ }}$
What would be the effect of on equilibrium if
A. Pressure is increased
B. Temperature is increased

Answer 1

The effect of change in pressure and temperature on the equilibrium is given by Le Chatelier’s principle. The equilibrium will automatically shift in that position where there is change of physical parameters like temperature, volume and pressure. This shifting of equilibrium can be in both forward and backward direction depending on the change.

Complete answer:
Whenever there is a change of temperature, volume and pressure in the equilibrium then the equilibrium will shift automatically against the change of direction. Thus equilibrium has a tendency to oppose that change. The principle which governs us about the shifting of equilibrium is given by Le Chatelier and known as Le Chatelier’s principle.
A.Effect of change in pressure:
According to Le Chatelier principle, whenever the pressure of a system increases, then the equilibrium will tend to shift in that side which has a lesser number of moles of gas. From the above reaction we can observe that reactants have three moles of gas while the product has only two moles of gas. Therefore on increasing pressure the reaction will proceed forward at a faster rate than at normal pressure.
B. Change in temperature:
According to Le Chatelier principle, for exothermic reactions the increase in temperature will decrease the formation of products as it will tend to reduce the energy of the reaction. Therefore we can say that on increasing temperature reaction will be reversed or equilibrium will shift in backward direction.

Note:
When we increase the pressure of the system we are indirectly reducing the volume of the system. Thus the Le Chatelier principle will work in the opposite manner as for change in pressure. The above reaction is exothermic in nature because the heat energy is mentioned at the product's side. If it is mentioned as a reactant side then it will be an endothermic reaction.