A System at Equilibrium Will Change in Response to Changing Temperatures
Chemical reactions at equilibrium are endothermic in one direction and exothermic in the opposite direction.
Endothermic means to absorb heat, and exothermic means to radiate heat. Now according to La Chatlier’s Principle, an increase in the temperature of a system at equilibrium will shift the reaction in the direction that absorbs the heat energy. So an increase in temperature shifts to the endothermic side, and a decrease in temperature shifts to the exothermic side.
Likewise, equilibrium constants are sensitive to changes in temperature. So for exothermic reactions, increasing temperature increases the equilibrium constant.
For endothermic reactions, increasing temperature decreases the equilibrium constant. Now right here we have the formation of ammonia, and the formation of ammonia is exothermic. So here increasing temperature would shift the reaction to the left and decrease the equilibrium constant.