Which one of the following conditions will favour maximum formation of the product in the reaction.
` A_2(g) +B_2(g) hArr X_2(g) , Delta rH =-XkJ ? `

Options

A. High temperature and high pressure
B. Low temperature and low pressure
C. Low temperature and high pressure
D. High temperature and low pressure

Answer

C

Explanation

Key Concept The given question is based upon Le-Chatelier's principle. According to this principle, if a stress is applied to a reaction mixture at equilibrium, reaction proceeds in such a direction that relieves the stress.
The given reaction is
`A_(2)(g)+B_(2)(g) hArr X_(2)(g), Delta_(r )H=-X kJ`
According to Le-Chatelier's principle, with increase in temperature the equilibrium shifts in the direction of endothermic reactions heat is absorbed).
Alternatively, the decrease in temperature shifts the equilibrium towards the direction of exothermic reaction (i.e. heat is produced).
`therefore A_(2)(g)+B_(2)(g) overset("Endothermic")underset("Exothermic")hArr X_(2)(g)`
Similarly, an increase in pressure will shifts the equilibrium to that direction which leads to decrease in total number of gaseous moles. Whereas, a decrease in the pressure will shift the equilibrium to that direction which leads to an increase in total number of gaseous moles.
For, `A_(2)(g)+B_(2)(g) hArr X_(2)(g)`
`Deltan_(g)=1-2=-1`
Thus, low temperature and high pressure will favour maximum formation of the product in the given reaction.