What is collision theory?
Two particles must have energy equal to or greater than the activation energy for a reaction to occur, and collide at the correct orientation
Define ‘activation energy’
Ea is the minimum energy required for a reaction to occur
5 things to be aware of with Maxwell-Boltzmann’s distributions
- No particles have 0 energy: the line doesn’t touch 0
- Cross the original line only once
- Peak shifts right/left
- Peak shifts up/down
- Area under line remains same
What does the area under the line in a Maxwell-Boltzmann distribution show?
The number of particles reacting
Axes on Maxwell-Boltzmann distribution?
y: no. of molecules
x: energy
Peak of Maxwell-Boltzmann distribution?
Most probable energy
Why does a small increase in temperature significantly increase the rate of reaction?
Significantly more particles have energy equal to or greater than the minimum activation energy required
How do you increase the rate of reaction?
- Increase temperature
- Increase concentration of reactants
- Increase pressure
- Increase surface area
Effect of an increased temperature on the rate of reaction?
- Particles have greater kinetic energy
- Move faster
- Greater frequency of collisions
= increased rate of reaction
Effect of an increased concentration of reactants on the rate of reaction?
- Particles are closer together
- Greater frequency of collisions
= increased rate of reaction
When does increasing the concentration of reactants change the rate of reaction?
In SOLUTION
When does increasing the pressure change the rate of reaction?
A GASEOUS reaction
Effect of an increased pressure on the rate of reaction?
- Particles are closer together
- Greater frequency of collisions
= increased rate of reaction
Effect of an increased surface area on the rate of reaction?
- More reaction sites
= increased rate of reaction
Maxwell-Boltzmann distributions are used for reactions in what states?
Gaseous/solutions
Average energy of particles is lower or higher than most probable energy?
Lower
Effect of increased temp on Maxwell-Boltzmann distribution?
Peak is lower and further to the right, as more particles have greater energies. Area underneath line is the same.
Do catalysts impact the overall enthalpy change of a reaction?
No!
What is a catalyst and how do they work?
- A substance that increases the rate of a chemical reaction
- without being changed in chemical composition or amount (not used up)
- They work by providing an alternative reaction route of lower activation energy.
