Consider the following reaction:
`2A(g)+B_(2)(g)hArr 2AB(g),DeltaH lt0`. How can the yield of AB(g) be increased?

Explanation

(i) For the reaction `Delta H lt 0`, so it is an exothermic reaction. According to Le Chatelier's principle, if the temperature of an exothermic reaction at equilibrium is decreased, the equilibrium of the reaction shifts to the right. So, the decrease in temperature will result in higher yield of AB(g).
(ii) The given reversible reaction is associated with the decrease in number of moles `[Deltan=2-(2+1)=-1]`
In the forward direction. so, according to Le Chatelier's principle, if the pressure is increased at the equilibrium of the reaction, the equilibrium shifts to the right, thereby increasing the yield of AB(g).
(iii) At constant temperature and volume, if the reactant A(g) or `B_(2)(g)` is added to the reaction systemm at equilibrium, then, according to Le Chatelier's principle, the equilibrium of the reaction will shift to the right. as a result, the yield of AB(g) will increase.