Exothermic and Endothermic

What is an exothermic reaction?

A reaction that gives out heat to its surroundings, causing the temperature to rise

What is an endothermic reaction

A reaction that absorbs energy from its surroundings, causing the temperature to drop

Give two examples of exothermic reactions

Combustion
Neutralisation (acid+alkali)
Oxidation reaction

Give examples of endothermic reactions

Photosynthesis
Dissolving salts into water

How do bond energies determine if a reaction is exothermic or endothermic?

Breaking bonds→require energy
Forming bonds→releases energy
More energy released than absorbed→exothermic
More energy absorbed than released→endothermic

What happens to the temperature of the surroundings in exothermic vs endothermic reactions?

Exothermic→temperature rises
Endothermic→temperature loses

How can you tell from an energy profile diagram if a reaction is exothermic or endothermic?

Exothermic → products lower energy than reactants

Endothermic → products higher energy than reactants

Give one everyday use of an exothermic reaction and one of an endothermic reaction.

Exothermic reaction→hand warmers
Endothermic reaction→photosynthesis

If a reaction absorbs more energy breaking bonds than it releases forming new bonds, is it exothermic or endothermic?

Endothermic, because energy is taken from its surroundings