Energy level diagrams
Chart showing the energy in the reactants and products, and the difference in energy between them. are used to model The capacity of a system to do work or the quantity required for mechanical work to take place. Measured in joules (J). For example, a man transfers 100 J of energy when moving a wheelbarrow. changes during reactions. They show the relative energy levels of the A substance formed in a chemical reaction. and A substance that reacts together with another substance to form products during a chemical reaction..
Exothermic reaction
The energy level decreases in an Reaction in which energy is given out to the surroundings. The surroundings then have more energy than they started with so the temperature increases. reaction. This is because energy is given out to the surroundings.
Endothermic reaction
The energy level increases in an Reaction in which energy is taken in. reaction. This is because energy is taken in from the surroundings.
Question
Look at the energy level diagrams below. Which reaction is more exothermic?
The reaction shown by the second diagram is more exothermic. There is a greater difference in energy between the reactants and products. The green arrow is longer.