CHEMISTRY COMMUNITY

By looking at energy profiles, how can you tell if it is showing an endothermic or exothermic reaction?

Generally, if the reactant energy is higher than the product energy, the reaction is exothermic, and vice versa for endothermic.

This is a good video explaining exothermic vs endothermic reactions.
https://www.youtube.com/watch?v=JRIm_a2LDPM

When the reactants activation energy is higher than the products, then it is exothermic. In this case, potential energy is higher for reactants than products. When the products activation energy is higher than the reactants, then it is endothermic. In this case, the potential energy of the reactants are lower.

You can tell it is exothermic when the activation energy is higher for reactants than it is for products. If the activation energy for products is higher than for reactants then the reaction is endothermic.

When reactant energy is higher than the product it is exothermic because energy is being released but if the reactant energy is lower than the product, it is endothermic because energy is required.

It is an exothermic reaction when the activation energy of the reactants are higher than the products. If the activation energy of the products is higher than the reactants, then it is an endothermic reaction.

If activation energy is higher than products, exothermic. If higher than reactants, endothermic.

An exothermic reaction is one where the reactants have more energy than products. Exothermic releases energy, which is why the reactants should have more energy.

If reactant energy is higher than the product energy, the reaction is exothermic and the opposite for endothermic.

Also just to add on, If the enthalpy is negative, the reaction is exothermic because heat is being released. If the enthalpy is positive, the reaction is endothermic because heat is being taken up by the rxn

A reaction is exothermic when the energy of the reactants is higher than the energy of the products. The energy difference is what is released into the surroundings as heat.

A reaction is endothermic when the energy of the reactants is lower than the energy of the products. The energy difference is what is required from the surroundings for the reaction to occur.

Exothermic reactions will have reactants higher than products and vice versa for endothermic.

A reaction is exothermic when the reactants have more energy than products. Vice verso for endothermic.

With reaction profiles to get delta H you have to subtract the end of the graph (products) by the beginning of the graph (reactants). So you have to remember that EXOTHERMIC reactions release energy into their surroundings meaning there is a loss of energy from the system ( meaning delta H = - ). So for exothermic reactions the end of the graph has to be lower than the beginning of the graph. And for ENDOTHERMIC reactions the end of the graph has to be higher than the beginning of the graph.