# Collision theory

Notes on the collision theory and factors affecting rate of reaction. Please leave comments x

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Natasha Naeem 12DJH
Collision Theory
Rate of reaction- The change in concentration (or gas produced) in a given period of time.
This measures the speed of the reaction.
Activation Energy- The minimum energy that a particle needs in order to react; the energy
(enthalpy) difference between the reactants and the transition state.
How factors affect the rate of reaction:
Concentration:
As concentration increases (of a solution)- If
there are more particles present in a given
volume, collisions are more likely, therefore
the reaction rate would be faster. However,
as a reaction proceeds, the reactants are
used up and their concentration falls. So, in
most reactions the rate of reaction drops
as the reaction goes on.
Pressure: As pressure increases (of a gas reaction)- This has the same effect as
increasing the concentration of a solution, there are more molecules or atoms in a given
volume so collisions are more likely.
Temperature: As temperature increases- This increases the speed of the molecules,
which in turn increases both their energy and the number of collisions.
Surface Area:
As surface area increases (of solid
reactants)- The greater the total
surface area of a solid, the more of its
particles are available to collide with
molecules in a gas or liquid.