Energy Change & Rates of Reactions

Heat of Reaction (triangle H)

The net change of chemical potential energy of the system

Exothermic Reactions

Reactions which transform chemical potential energy into thermal energy

Endothermic Reactions

Reactions which transform thermal energy into chemical potential energy

Activation Energy

The minimum energy required to start a chemical reaction or The energy required to form the activated complex

Activated Complex

A high energy, unstable, transition state between the reactants and the products

Reaction Rate

The change in amount or concentration per unit time of either a reactant or product

Catalyst

A substance that increases the rate of the reaction but remains unchanged at the end of the reaction