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Chemistry vocabulary · Energy, Reaction Rates and Equilibrium

Activation energy

Meaning in chemistry, with examples

nounCommon term

In chemistry, activation energy means: The minimum energy that reacting particles need to collide successfully and start a reaction. Catalysts work by lowering it.

In Turkish: aktifleşme enerjisi, aktivasyon enerjisi

How it is used

Used in kinetics and on energy diagrams. You calculate it from rate data with the Arrhenius equation; its symbol is Eₐ, usually in kJ/mol. A high activation energy means a slow reaction at room temperature.

Example sentences

  1. The catalyst lowers the activation energy, so the reaction runs at room temperature.

  2. Determine the activation energy from a plot of ln k against 1/T.

Common collocations

  • lower the activation energy
  • high activation energy
  • energy barrier
  • Arrhenius equation
  • catalystA substance that speeds up a chemical reaction without being used up. It works by offering a different pathway with a lower activation energy.
  • reaction rateHow fast reactants are used up or products are formed, usually measured as a change in concentration per unit time, for example in mol/L per second.
  • exothermicDescribes a reaction or process that releases heat to the surroundings, so the temperature rises. Its enthalpy change (ΔH) is negative.
  • enthalpyThe heat content of a system at constant pressure. Chemists usually measure its change, ΔH, which shows how much heat a reaction gives out or takes in.

This word in other fields

The same English word can have a different meaning in another field:

More terms: Energy, Reaction Rates and Equilibrium

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