When increasing temp of an exothermic rxn which hasn't yet reached equilibrium, why is less product produced?

Question

I thought more would be produced...

To: Hc. I got it now thanks!

Answer 1

Since the reaction is exothermic, you can kind of think of heat as a "product". So, if you use LeChatlier's Principle, if you add a product to a reaction, the equilibrium will be established so that you'll form less of the other products.

Answer 2

Due to LeChatlier's principle, whenever more of one thing is present on one side of a reaction equation, the reaction will be great in the other direction or less in that direction.

In an exotherm. rxn,

Reactants <--> Products + Heat

When there is more heat on one side of the equation, the reaction will not proceed as readily toward the products. The equation will reach an equilibrium with less of the reactants reacting and less of the products being produced.

I agree it is somewhat counterintuitive. That's probably because we are used to exothermic reactions happening because of heat, e.g., you need a match or spark to set a piece of paper on fire. Many exothermic reactions like combustion require a certain amount of energy to initiate the reaction. However, at higher temperatures, reactants are less likely to react because there is already so much heat energy on the other side of the equation. For instance, some ramjet engines are limited in their power because their intakes get so hot they can't support additional combustion of jet fuel.

Answer 3

The amount of reactants is constantly being depleted hence less product is produced as the reaction proceeds.

Answer 4

Because Rln K = -/\H/T +/\S so as T increases this causes the value of the equilibrium constant(K) to become smaller (less product).