3D GRIDBUILDING - SCIENCE - CHEMISTRY

COLLISION THEORY

The collision theory explains why altering the conditions - temperature, pressure, etc - under which a chemical reaction takes place, will alter the rate of reaction.


For any reaction to occur, there must be collisions between particles of reactants.


Only some of these collisions (called fruitful collisions) will cause a reaction, since not all collisions contain enough energy to start the particular reaction.


Any change to the system which increases the energy within it, increases the energy of some of the particles (eg addition of heat causes the particles to gain kinetic energy), so the number of fruitful collisions, and therefore the overall rate of reaction, will increase.


The opposite is also true: for example, reducing the temperature will reduce the particles' kinetic energy, so there will be less energy in the collisions and fewer will be fruitful.


Anne Evans