CLASS 7 · LEARNING KNOWLEDGE
Energy in chemical reactions – basic principles
How it works
In chemical reactions, energy is either absorbed or released. Exothermic reactions release energy, usually in the form of heat or light. Endothermic reactions require an input of energy in order to proceed. The change in energy can be observed through a change in temperature, emission of light, or other effects. The total energy is conserved (law of conservation of energy); it is only transformed. Activation energy is the minimum energy needed for a reaction to start.
Note
Chemical reactions are either exothermic (energy release) or endothermic (energy absorption); in the process, energy is transformed, not destroyed.
Chemical reactions are either exothermic (energy release) or endothermic (energy absorption); in the process, energy is transformed, not destroyed.
An example
Which statement best describes an exothermic reaction?
An exothermic reaction releases energy to the surroundings, e.g. as heat. This can be recognized by the reaction vessel warming up.
Try it yourself now
50 Exercises
To the learning unit →Own explanation and own practice exercises by AmyMath. Subject reference framework: Chemistry. The topic assignment may vary by federal state.