Summary Rates of Reactions

RATES OF REACTIONS

Collison theory states that in order for two particles to react they must collide.
Particles do not react in every collision. If they react the collision is successful.
The greater amount of successful collisions per second the greater the rate of
the reaction


SUCCESSFUL COLLISIONS
1) Reactant particles must collide
2) The particles must collide with sufficient kinetic energy (activation
energy)
Activation energy – the minimum energy required to start a chemical reaction
3) The reactant particles must collide with the correct orientation
If they are not facing the correct way they will bounce off of each other

, ENERGY CHANGES IN REACTIONS
To break a chemical bond, energy is taken in which is endothermic
Endothermic reaction – reactions which transform thermal energy into
chemical potential energy
To form a chemical bond, energy is given out which is exothermic
Exothermic reaction – reactions which transform chemical potential energy
into thermal energy



POTENTIAL ENERGY PROFILES




Activated complex – a high energy, unstable transition state between reactants
and products
Heat of the reaction (ΔH) – the net change of chemical potential energy of a
system
ΔH = Hf - Hi
ΔH = EP - ER
ΔH = Ein - Eout