Energy Changes
Activation energy: The minimum amount of energy for particles to collide with
in order for a
successful reaction to occur.
*Alkaline batteries: Alkaline batteries are non-rechargeable. In non-
rechargeable cells and
batteries the chemical reactions stop when one of the reactants has been used
up.
*Battery: Batteries consist of two or more cells connected together in series to
provide a
greater voltage.
*Chemical cells: Cells contain chemicals which react to produce electricity
Endothermic reaction: An endothermic reaction is one that takes in energy
from the
surroundings so the temperature of the surroundings decreases. In an
endothermic
reaction, the energy needed to break existing bonds is greater than the energy
released from forming new bonds.
Exothermic reaction: An exothermic reaction is one that transfers energy to the
surroundings so the temperature of the surroundings increases. In an
exothermic reaction,
the energy released from forming new bonds is greater than the energy
needed to
break existing bonds.
*Fuel cells: Fuel cells are supplied by an external source of fuel (eg hydrogen)
and oxygen
or air. The fuel is oxidised electrochemically within the fuel cell to produce a
potential
difference
