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Collision theory and rates of reaction

Some reactions are slow, such as rusting, and some are fast, like burning. The rate of reaction depends on the temperature and concentration of the reactants, and the surface area of any solid reactants.

The rate of reaction can be found by measuring the amount of reactant used up, or the amount of product formed, in a given time. Catalysts increase the rate of a reaction without being changed themselves by the end of the reaction.

Collision theory

Different reactions can happen at different rates. Reactions that occur slowly have a low rate of reaction. Reactions that happen quickly have a high rate of reaction. For example, rusting is a slow reaction: it has a low rate of reaction. Burning and explosions are very fast reactions: they have a high rate of reaction.


For a chemical reaction to occur, the reactant particles must collide. But collisions with too little energy do not produce a reaction.

The particles must have enough energy for the collision to be successful in producing a reaction.

The rate of reaction depends on the rate of successful collisions between reactant particles. The more successful collisions there are, the faster the rate of reaction.

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