Kinetics

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Kinetics
Collision Theory and Ea
The collision theory states that particles collide with enough energy and with the correct orientation to break the bonds
between them. This is associated with activation energy which is the minimum amount of energy needed for successful
collisions to occur.
Factors Affecting the Rate of Reaction (Ea)
Increased surface area:
Increased particles at surface meaning that there are more collisions, which allows for more successful collisions,
thus increasing the rate of reaction
Increased temperature:
The particles move faster with more kinetic energy meaning that they collide more frequently which allows for
more successful collisions and an increased rate of reaction
Increased concentration (solutions):
There are more particles which means that there are more collisions occurring allowing for more successful
collisions and an increased rate of reaction. However, as the reactants are used up the concentration gradient falls
meaning the rate of reaction will drop
Increased pressure (gases)
There are more particles which means that there are more collisions occurring allowing for more successful
collisions and an increased rate of reaction.
Decreased volume:
There is the same no. of particles but a smaller area meaning that there are more collisions allowing for more
successful collisions and an increased rate of reaction
Using a catalyst:
These are substances that will increase the rate of chemical reactions without being chemically changed.
Catalysts
These are substances that affect the rate of chemical reactions without being chemically changed. They speed up
reactions to reduce cost. They are not used up so can be used again.
Advantages of Catalysts
Lower energy demands
therefore less CO 2 produced
less environmental impact
lower production costs
Catalytic Converters
These are used inside petrol-engine cars and reduce the number of polluting gasses produced by the engines. They
are made of ceramic material arranged in a honeycomb shape which is coated with platinum and rhodium. The shape
of the converters give it a large surface area which means less of the reactants is used up ­ only small amounts of
platinum and rhodium are needed.

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When the polluting gasses pass over the catalyst they trigger a series of chemical reactions that produce less harmful
products:
Carbon Monoxide + Nitrogen Oxides Nitrogen + Carbon Dioxide
Hydrocarbons + Nitrogen Oxides Nitrogen + Carbon Dioxide + Water
Maxwell-Boltzmann Distribution
The Maxwell-Boltzmann distribution is the shape formed on the graphs, which are used to show the distribution if
energy amongst particles.…read more

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Catalysts ­ With the use of a catalyst the activation energy needed is lowered
meaning that the `minimum activation energy' line is moved to the left…read more

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