ScienceVerseLearning path: Reaction Energy
The concepts to learn before Reaction Energy, in order. Each step links to its page and, where one exists, its quiz.
Sign in to see which steps you have already opened and which quizzes you have completed.
Your path
- Chemical ReactionsDirect prerequisite
A chemical reaction rearranges atoms: bonds in the starting substances (reactants) break and new bonds form, making new substances (products) with different properties. No atoms are created or destroyed, so mass is conserved and a chemical equation must balance. For a reaction to happen at all, particles must collide in the right orientation with at least the activation energy, which is why temperature changes reaction rates.
- EnergyDirect prerequisite
The capacity to do work, taking forms such as kinetic energy (associated with motion) and potential energy (associated with position or configuration, such as height in a gravitational field). The total energy of an isolated system is conserved: energy changes form but is never created or destroyed.
- Reaction EnergyYour goal
Every chemical reaction involves an energy change, because breaking bonds absorbs energy and forming bonds releases it. If more energy is released than absorbed, the reaction is exothermic (ΔH < 0) and warms its surroundings; if the reverse, it is endothermic (ΔH > 0). Separately, almost every reaction must first climb an energy barrier, the activation energy, which sets how fast it goes — and which a catalyst lowers without being used up.