Explaining energy changes in reactions - Higher - Energy, rates and reactions - AQA Synergy - GCSE Combined Science Revision - AQA Synergy

Explaining energy changes in reactions - Higher

is transferred when are broken or are formed.

Type of process
Breaking bonds	Endothermic
Forming bonds	Exothermic

Heat energy transferred
Breaking bonds	Taken in
Forming bonds	Given out

During a chemical reaction:

The difference between the energy needed to break bonds and the energy released when new bonds are made determines the type of reaction.

A reaction is:

if more heat energy is released in making bonds in the products than is taken in when breaking bonds in the reactants
if less heat energy is released in making bonds in the products than is taken in when breaking bonds in the reactants