Rate= change of concentration of reactant / timeRate depends on concentration and not amount.
Diapositiva 2
The collision theory of reaction rates
The collision theory makes the following assumptions:
For a reaction to occur, the particles of the reactants must collide with one another
The particles must have sufficient energy to react. This is known as activation energy. Collisions which have the required activation energy are called successful collisions.
To increase the rate, it is necessary to increase the frequency of successful collisions.
Diapositiva 3
Factors which affect rate
ConcentrationIncrease in concentration means an increase in rate.More particles in a given volume. Particles collide more often, therefore more successful collisions per second.TemperatureIncrease in temperature means an increase in rate.Particles have more energy. More collisions have the required activation energy, therefore more successful collisions per second.Surface AreaIncrease in surface area means an increase in rate.More particles in contact with each other reactant. Particles collide more often, therefore more successful collisions per second.
Diapositiva 4
Effect of catalysts on rate
A catalyst is a substance that increases the rate of reaction but is chemically unchanged at the end of the reaction.Catalysts provide an alternate pathway for the reaction. This has a lower activation energy than the original pathway. This means that more of the collisions taking place will have the necessary activation energy. Therefore there will be more successful collisions per second.
