Collision theory
For partiles to react they must
- collide
- at or above activation energy
- in the correct orientation
Define catalyst
A substance which increases rate of reaction by providing an alternate reaction pathway with lower activation energy, without being used up
Homogenous catalyst
A catalyst in the same phase/physical state as the reactants
Heterogenous catalyst
A catalyst in a different phase/physical state as the reactants
Benefit of using catalysts?
- Benefits both economially and sustainably
- A lower temperature is needed for the reaction to take place
- Less energy is needed
- Less fossil fuels are used and CO2 released
How does concentration affect rate of reaction?
- Higher conc. = higher rate
- More particles in a given volume
- Higher frequency of successful collision
How does temperature affect rate of reaction?
- Higher temp. = higher rate
- Particles have higher kinetic energy
- More particles at/above activation energy (when colliding)
- Particles move faste (increase in frequency of collision)
- Higher frequency of successful collision
How do catalysts affect rate of reaction?
- Lower activation energy
- More particles at/above activation energy
- Higher frequency of successful collision
Dynamic equilibrium
Rate of the forward and backward reactions are equal/ concentration of reactants and products are constant, in a closed system
Le Chatelier’s principle
When a change occurs in a mixture at equilibrium, the equilibrium will shift to oppose the change
Kc?
-product of conc. of products, each to the power of its coefficient/product of conc. of reactants, each to the power of its coefficient
How does Kc determine equilibrium position
Kc>1 to the right
Kc<1 to the left
Mechanism of heterogenous catalysts?
- adsorption of reactants onto surface of catalyst
- bonds weakened and broken in reactants
- new bonds formed
- products diffuse away from surface - desorption
What reaction does a catalytic converter catalyse?
CO + 2NO -> CO2 + N2
