This document summarizes the key differences between exothermic and endothermic reactions. Exothermic reactions release heat to their surroundings and decrease in energy, while endothermic reactions absorb heat from their surroundings and increase in energy. Examples of each type of reaction are also provided.

1. Thermochemistry
Exothermic Reaction Endothermic Reaction
 Is a reaction that release  Is a reaction that absorb
heat to the surrounding heat from the surrounding
 Temperature of the  Temperature of the
surrounding increase surrounding decrease
 Energy level diagram  Energy level diagram
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2. Thermochemistry
Exothermic Reaction Endothermic Reaction
 Energy of the products is  Energy of the products is
less than reactants. more than reactants.
 ∆H = negative  ∆H = positive
 Energy for bond breaking is  Energy for bond breaking is
less than energy from bond more than energy from
formation bond formation
 More energy released  More energy absorbed for
during bond formation than bond breaking than energy
energy absorbed for bond released during bond
breaking formation
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3. Thermochemistry
Exothermic Reaction Endothermic Reaction
 Examples:  Examples:
 Neutralization reaction  Photosynthesis
 Reaction between acids and  Dissolving ammonium salts in
metals water
 Adding water to concentrated  Decomposition of metal
acids carbonate
 Reaction between reactive  Decomposition of metal
metals with water nitrates
 Respiration
 Burning of fuels
 Haber process
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