Effect of Temperature On Reaction Rate (Oxford AQA International A Level Chemistry)
Revision Note
Written by: Philippa Platt
Reviewed by: Stewart Hird
Temperature & Rate of Reaction
When the temperature of a reaction mixture is increased, the particles gain more kinetic energy
This causes the particles to move around faster resulting in more frequent collisions
Furthermore, the proportion of successful collisions increases, meaning a higher proportion of the particles possess the minimum amount of energy (activation energy) to cause a chemical reaction
With higher temperatures, the Boltzmann distribution curve flattens and the peak shifts to the right
Changing the temperature
Therefore, a small increase in temperature causes an increased rate of reaction due to:
There being more effective collisions as the particles have more kinetic energy, making them move around faster
A greater proportion of the molecules having kinetic energy greater than the activation energy
Worked Example
The image below shows, for a given temperature T, a Boltzmann distribution of the kinetic energy of the molecules of a mixture of two gases that will react together.
Draw a new distribution curve, clearly labelled T2, for the same mixture of gases at a lower temperature, T2.
Answer:
As the temperature is lower the peak should be to the left of the original as the average energy of the molecules is lower
The peak is higher as more molecules have the average energy
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