Effect of temperature

If the temperature of a system at equilibrium is changed, the system responds by shifting the equilibrium in whichever direction tends to counteract (absorb) that change in temperature.

Consider ammonia synthesis again. Here the forward reaction is exothermic (heat is released as $NH_3$ forms) while the reverse reaction is endothermic (heat is absorbed as $NH_3$ decomposes). If the system's temperature is raised (heat energy is supplied), it responds by decomposing some of the ammonia back into nitrogen and hydrogen, since that is the direction that absorbs the extra heat supplied. Conversely, if the temperature is lowered, the system responds by forming more ammonia from nitrogen and hydrogen, since that is the direction that releases heat, partially offsetting the drop in temperature. …