posted by a Canadian on .
I'm reviewing for a test and I'm on Le Chatelier's principle. Decreasing the temperature of an exothermic reaction shifts the equilibrium to the right?
I understood this weeks ago but now I can't remember.
Wouldn't decreasing the temperature cause there to be less collisions between reactants? Because in an exothermic reaction, reactants have more energy? (the products' collisions will be lessened too, but wouldn't it be more significant for the reactants since they have more energy?) So less collisions between reactants means the rate of the reverse reaction will Be less than the rate of the forward reaction, so the equilibrium system will shift to the left and produce more reactants to reastablish equilibrium?
I know that's wrong but that's what I think right now so I would really appreciate an explanation, I'm pretty confused.
You're making it far too complicated.
A + B ==> C + heat.
That's an exothermic reaction since heat is emitted. Since a system in equilibrium will try to undo what we do to it, if we ADD heat, the reaction will shift so as to try to use up the added heat. If it shifts to the right more heat is released. Hardly what we're looking for. If it shifts to the left heat is used. So it shifts to the left.