endothermic and exothermic reactions

In an exothermic reaction

the products have less energy than the reactants

In an endothermic reaction

the products have more energy than the reactants

Activation energy

the energy required to start a chemical reaction

In order to be exothermic, a reaction must:

release more energy from making bonds than it absorbs in order to break bonds from the reactants (heats up)

In order to be endothermic, a reaction must:

have a greater input of energy to break bonds than it releases when new bonds are formed (cools down)

Endothermic

energy is required to break intermolecular forces and seperate molecules

Exothermic

energy is released when intermolecular forces form between molecules

Changing state =

breaking bonds or forming bonds

Forming bonds _____ energy

loses

Breaking bonds _____ energy

needs

The flat section of heating curve shows (time vs temp)

that supplied energy is being used to break attractive forces so the temperature doesn’t change

The sloped section of heating curve shows (time vs temp)

where the temperature rises due to heat supplied, leads to an increase in kinetic energy of the particles in the substance