Rate of reactions. Image credit about.com

Rate of reactions. Image credit about.com

ZIMSEC O Level Combined Science Notes: The speed of reactions

  • Reactions happen at different speeds
  • This is because there are a number of factors that influence the speed of a reaction even between the same reagents
  • Reagents are the chemicals that are participating in a chemical reaction
  • The rate of a given reaction can be altered by changing one or a any number of the factors/conditions that affect the speed of a reaction
  • A reaction occurs between substances (reagents) when their particles collide
  • The rate of the reaction therefore increases if there is an increase in these collisions

Factors affecting the rate of a reaction

FactorHow it affects a rection
Particle sizeThe smaller the particle size the faster the reaction.
Crushing the substance into smaller pieces increases the surface area and thus the rate of the reaction.
Large particles slow the reaction down
ConcentrationThe higher the concentration the faster the rate of the reaction.
Diluting on e the reagents e.g. the acid slows down the rate of a reaction
TemperatureThe higher the temperature the faster the reaction.
Increasing the temperature of the reagents increases the rate of the reaction as more and more molecules collide into each other
CatalystWhen the appropriate catalyst is used the rate of reaction is sped up

To access more topics go to the Combined Science Notes page.

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