Which the following reaction will get affected by increasing the pressure? Also, mention whether change will cause the reaction to go into forward or backward direction.
(i) `COCl_(2) (g) hArr CO(g) + Cl_(2)(g)`
(ii) `CH_(4)(g) + 2S_(2)(g) hArr CS_(2)(g) + 2H_(2)S(g)`
(iii) `CO_(2)(g) + C(s) hArr 2CO(g)`
(iv) `2H_(2)(g) + CO(g) hArr CH_(3)OH(g)`
(v) `CaCO_(3)(s) hArr CaO(s) + CO_(2)(g)`
(vi) `4NH_(3)(g) + 5O_(2)(g) hArr 4NO(g) + 6H_(2)O(g)`

Explanation

Reactions affected will be those in which `(n_(p) != n_(r))_(gaseous)` .Hence, reactions (i) and (iii) will be affected. By applying Le Chatelier’s principle, we can predict the direction. Increase of pressure will shift the equilibrium to the side in which the number of moles is less.
(i) `n_(p) = 2, n_(r) = 1, i.e., n_(p)>n_(r)` reaction will go in the backward direction
(ii) `n_(p) = 3, n_(r) = 3, i.e., n_(p)=n_(r)` reaction will not be affected by pressure
(iii) `n_(p) = 1, n_(r) = 3, i.e., n_(p)