Endothermic & Exothermic Reactions and Enzymes

by Shayna Lof

Terms

System: where the reaction is taking place

Activation Energy: the energy needed to start a reaction

Reactants: the substances that are started with before the reaction takes place

Products: the end result after the reaction has taken place

Exothermic Reactions

A reaction in which the energy comes out of the system into the surrounding area.

Ex. A campfire, the heat energy from the fire warms the area around the fire.

Endothermic Reactions

A reaction in which energy needs to be put into the system.

Ex. A fried egg, the energy from the stove cooks the egg.

Exothermic Reaction

Some energy needs to be put into the reaction before the reaction takes place. The reactants have more energy that the products; energy is lost.

Endothermic Reaction

Once the reaction starts energy is put into the reaction and the products have more energy than the reactants.

Enzymes

Enzymes speed up a reaction but are not used up during the reaction. They lower the activation energy that is needed to start the reaction.

The right enzyme should cause the right substrate (reactant) to fit into it, the enzyme will break the substrate apart, and the reaction will speed up.

Sources

Fraser, D. LeDrew, B. Vavitsas, A. White-McMahon, M (2012) Nelson Education Ltd, Biology 12

Khan academy (2021) retrieved from: https://www.khanacademy.org/science/biology/energy-and-enzymes

Softschools (2005-2020) retrieved from: https://www.softschools.com/difference/endothermic_vs_exothermic/442/