Energy Changes - P1T5

Activation energy

The minimum amount of energy needed for particles to collide with for a successful reaction to occur.

*Alkaline batteries

Non-rechargeable batteries. The chemical reactions stop when one of the reactants is used up.

*Battery

A device consisting of two or more cells connected in series to provide a greater voltage.

*Chemical cells

Cells that contain chemicals which react to produce electricity.

Endothermic reaction

A reaction that takes in energy from the surroundings, causing a temperature decrease. Energy needed to break bonds > energy released from forming bonds.

Exothermic reaction

A reaction that releases energy to the surroundings, causing a temperature increase. Energy released from forming bonds > energy needed to break bonds.

*Fuel cells

Cells supplied by an external source of fuel (e.g. hydrogen) and oxygen. Fuel is oxidised electrochemically to produce a potential difference.

Overall energy change of the reaction

The difference between the energy required to break bonds in the reactants and the energy released when new bonds form in the products.

Reaction profile

A diagram that shows the relative energies of reactants and products, activation energy, and overall energy change of a reaction.

*Rechargeable cells

Cells that can be _____ as the chemical reactions are reversed by supplying an external electrical current.