Consider the following system at equilibrium where delta H° = -108 kJ, and Kc = 77.5, at 600 K. CO(g) + Cl2(g) <---> COCl2(g) If the VOLUME of the equilibrium system is suddenly decreased at constant temperature:

The reaction will shift rightwards, favoring the formation of more COCl2 (g).

Explanation:

Hello,

In this case, since the reaction is carried out in gaseous phase, and the change in the number of moles of the reaction is negative as shown below (consider stoichiometric coefficients, positive for products, negative for reactants):

By means of the Le Chatelier's principle, decreasing the volume always favors the direction that produces fewer moles, thus, this system will shift to right and produce more moles of product, that in this case is gaseous COCl2.

Regards.