Energy Changes Flashcards
What happens to energy in a chemical reaction?
It is conserved. The amount of energy at the end
of the reaction is the same as the amount of
energy at the start.
What is an exothermic reaction?
A reaction in which energy is transferred to the
surroundings so the temperature of the
surroundings increases.
What are examples of exothermic reactions?
Combustion, oxidation reactions and
neutralisation.
What are everyday uses of exothermic
reactions?
Self heating cans and neutralisation.
What is an endothermic reaction?
A reaction in which energy is transferred from
the surroundings to that the temperature of the
surroundings decreases.
What are examples of endothermic reactions?
Thermal decomposition and reaction of citric acid
and sodium hydrogencarbonate.
What are everyday uses of endothermic
reactions?
Sports injury packs.
What is activation energy?
The minimum amount of energy that particles
must have to react when the reacting particles
collide with each other.
What are reaction profiles?
A diagram that can be used to show the relative
energies of reactants and products. It shows the
activation energy and the overall energy change
of a reaction.
What happens to bonds during a chemical
reaction?
Energy is supplied to break bonds in the reactants
and energy is released when bonds in the
products are formed.
How can the overall energy change be
calculated?
Calculate the difference between the sum of the
energy needed to break the bonds in the
reactants and the sum of the energy released
when bonds in the products are formed.
