Exothermic and endothermic reactions
- Activation energy — the minimum amount of energy necessary for a reaction to occur.
Exothermic reactions
An exothermic reaction transfers energy to the surroundings, leading to an increase in surrounding temperatures. Bond making.
Endothermic reactions
An endothermic reaction takes in energy from the surroundings, leading to a decrease in the temperature of surroundings. Bond breaking.
Enthalpy change
- Enthalpy change — the transfer of thermal energy during a reaction.
How to calculate enthalpy change?
Total energy of reactants – Total energy of products
Enthalpy change is negative for exothermic reactions and positive for endothermic reactions.