2. Concentration
The higher the level of concentration (or pressure in
gases) the faster the reaction.
This is due to increased collisions between reacting
particles.
Factors affecting reaction rates
3. Surface area in solids
The larger the surface area of a solid the faster the
reaction. Finely divided substances have much larger
surface areas than large chunks of a solid.
This is due to increased collisions between reacting
particles.
Factors affecting reaction rates
4. Temperature
The higher the temperature the faster the reaction.
This is due to increased and more energetic collisions
between reacting particles.
A 10oC rise in temperature often results in a doubling
of the reaction rate.
Key point: at a higher temperature more
molecules have energy greater than the activation
energy.
Factors affecting reaction rates
10. Catalysts
Catalysts increase the rates of chemical reactions.
This is due a lowering of the activation energy for the
reaction.
Catalysts are not consumed in the reaction so in
theory they can be used over and over again. In
practice they are often contaminated and/or some is
lost in a process.
Factors affecting reaction rates