Kinetics Flashcards
What is a catalyst
A substance that increases the rate of a reaction but does not get used up
What is a homogenous catalyst?
One that is in the same state as the reactants and products and provides a pathway of lower activation energy by forming an intermediate
What is a heterogenous catalyst?
One that is in a different state to the reactants and products and works via chemisorption and provides a pathway of lower activation energy
What is chemisorption?
Reactant molecules are absorbed onto the surface of the catalyst, bonds are weakened and they are held in a more favourable position for the reaction
How do you measure the rate of a reaction
Gas volume against time or mass against time.
Gas syringe for gas volume, Container on a balance for mass over time the plot a graph
What four factors affect the rate of a reaction?
Temperature - Increased = increased energy for reacting particles
Pressure - Particles closer together
Concentration - More reacting particles
Presence of a catalyst Alternative route of lower activation energy
All of the above means increased number of collisions, increased number of successful collisions over a period of time, therefore increased rate
Draw an enthalpy level diagram for an exothermic reaction including the pathway if a catalyst is present
in book
What does a Maxwell-Boltzmann curve start at 0?
What does the total area under the graph represent?
No particles have no energy
The total number of particles present
Where would Ea move to if a catalyst was present?
It would move to the left so there was more area under the line because more particles have the activation energy
What happens to the shape of the curve when the temperature is increased? Draw it
Has a broader peak below the initial to the right and is above the initial line.
