Final answer:
An increase in temperature for an exothermic reaction will shift the equilibrium towards reactants, resulting in a decrease in the equilibrium constant and generally increase the rate of the reaction by providing more particles with the necessary activation energy.
Step-by-step explanation:
For an exothermic reaction, an increase in temperature can impact the equilibrium of the reaction. According to Le Châtelier's principle, if you add heat to the system, the equilibrium will shift to favor the endothermic direction to absorb the excess heat. Hence, increasing temperature will cause the equilibrium to shift to the left, favoring the reactants. Conversely, decreasing the temperature would shift the equilibrium to the right, favoring the formation of products, since the exothermic reaction releases heat to the surroundings, essentially 'replacing' the heat that has been removed.
Therefore, an increase in temperature for an exothermic reaction generally results in a decrease in the equilibrium constant (Keq), because it shifts the equilibrium towards the reactants. Additionally, increasing temperature usually increases the rate of the chemical reaction because it provides more particles with the necessary activation energy required for effective collisions.