Which of the following reaction will be favoured at low pressure?

Options

A. `H_(2(g))+I_(2(g)) harr 2HI_((g))`
B. `PCl_(5(g)) harr PCl_(3(g)) + Cl_(2(g))`
C. `N_(2(g))+O_(2(g)) harr 2NO_((g))`
D. `N_(2(g))+3H_(2(g)) harr 2NH_(3(g))`

Answer

B

Explanation

Al equilibrium, low pressure favours those reaction which are accompanied by increase in total number of moles and high pressure favours those reaction which takes place with decrease in total number of males. However, pressure is not dependent on an equilibrium reaction which proceeds with no change in total number of moles. Hence, the reaction
`PCl_(5(g)) harr PCl_(3(g))+Cl_(2(g))" "Delta_g-n_p-n_g=2-1=1`
is favored by low pressure.