A

Activation Energy

Ea; k = Ae^(−Ea/RT) (Arrhenius)
Quick Reference
Formula / NotationEa; k = Ae^(−Ea/RT) (Arrhenius)
Also Known AsEnergy of activation; threshold energy; Ea; Arrhenius activation energy

What is Activation Energy?

Activation energy (Ea) is the minimum amount of energy that reacting molecules must possess in order for a chemical reaction to occur. It represents the energy barrier that must be overcome for reactants to be converted to products. Catalysts work by providing an alternative reaction pathway with a lower activation energy.

Formula & Notation

Ea; k = Ae^(−Ea/RT) (Arrhenius)

Other Names / Synonyms: Energy of activation; threshold energy; Ea; Arrhenius activation energy

Properties & Characteristics

Measured in kJ/mol or J/mol; always positive; related to rate constant by Arrhenius equation: k = Ae^(−Ea/RT); can be determined from a plot of ln k vs 1/T; higher Ea → slower reaction at given temperature; catalysts reduce Ea without being consumed

Uses & Applications

Designing catalysts and inhibitors; understanding reaction mechanisms; controlling reaction rates in industrial processes; food preservation (refrigeration slows reactions by reducing molecular energy below Ea)

Safety Information

No direct hazard — a thermodynamic/kinetic concept. Reactions with low activation energies can proceed rapidly or explosively if initiated.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Activation Energy
Formula Ea; k = Ae^(−Ea/RT) (Arrhenius)
Synonyms Energy of activation; threshold energy; Ea; Arrhenius activation energy

Frequently Asked Questions

Activation energy (Ea) is the minimum amount of energy that reacting molecules must possess in order for a chemical reaction to occur. It represents the energy barrier that must be overcome for reactants to be converted to products. Catalysts work by providing an alternative reaction pathway with a lower activation energy.

More "A" Terms

View all "A" terms →
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z