Activation energy

Definition:

• Activation energy (EA) is the minimum energy required for a chemical reaction to occur.

Importance:

• Activation energy determines whether a reaction will happen and how quickly it will proceed.

Temperature and Kinetic Energy:

• Temperature measures the average kinetic energy of particles in a substance.

Effect on Reaction Rate:

High Activation Energy:

• If a reaction has a high activation energy, only a few particles have enough kinetic energy to collide successfully.
• This leads to slow reaction rates.
• Example: Combustion of large pieces of wood requires a high activation energy, resulting in a slow burn rate.

Low Activation Energy:

• Reactions with low activation energy involve a greater number of particles with the required energy.
• This leads to fast reaction rates.
• Example: Combustion of paper, which has a lower activation energy, burns rapidly.

Graphs:

• Activation energy can be represented on graphs that show how many molecules have enough energy to react.

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Activation energy

Effect of Temperature:

• Increasing temperature raises the kinetic energy of particles.
• This increases the number of particles with energy greater than the activation energy (Ek > EA).
• Consequently, higher temperature significantly increases the rate of reaction.
• Example: A 10°C temperature rise can double the rate of reaction.