5.5.1.2 Reaction profiles
For a reaction to take place the particles of the reactants must collide with enough energy.
Activation energy is the minimum amount of energy the particles must have to react.
Reaction profiles show:
a diagram for an exothermic or endothermic reaction
the energies of reactants and products
the activation energy
the overall energy change of a reaction
The overall energy change = energy of reactants - energy of products.
Reaction profile of an exothermic reaction
Q1. What is activation energy?
The minimum amount of energy the particles must have to react. (Energy needed to start a reaction.)
Q2. How do we calculate the overall energy change of a reaction?
overall energy change = energy of reactant – energy of product
Q3. The figure shows a reaction profile. What do labels A, B, C, D and E represent?
A - energy of reactants
B - progress of reaction
C - overall energy change
D - activation energy
E - energy
Q4. Explain why the reaction profile in the figure shows an exothermic reaction.
The energy of the reactants is higher than the energy of the products, this means that energy is lost to the surrounding.
Reaction profile of an exothermic reaction
Q5. The figure shows a reaction profile. What do labels A and B represent?
A - activation energy
B - overall energy change
Q6. Explain why the reaction profile in the figure shows an endothermic reaction.
The energy of the reactants is lower than the energy of the products, this means that energy is taken in from the surrounding.