大象传媒

Energy level diagrams

are used to model changes during reactions. They show the relative energy levels of the and .

Exothermic reaction

The energy level decreases in an reaction. This is because energy is given out to the surroundings.

Graph of energy against progress of reaction. Horizontal line represents reactants energy. Drops vertically as energy released. Horizontal line at a lower level represents products' energy.
Figure caption,
A downwards arrow shows that energy is given out

Endothermic reaction

The energy level increases in an reaction. This is because energy is taken in from the surroundings.

Graph of energy against progress of reaction. A horizontal line represents the reactants' energy. It rises vertically as energy is absorbed. A horizontal line at a higher level then represents the products' energy.
Figure caption,
An upwards arrow shows that energy is taken in

Question

Look at the energy level diagrams below. Which reaction is more exothermic?

Two graphs of the effect of energy being released from reactants.