Topic 9 Flashcards
What is the formula for rate of reaction + how do you measure rate of reaction?
- How much a product is being formed OR How much a reactant is being used up
- Then plot on a graph and find gradient (depending on the given time)
Formula Shown Below
What is the three main points of Collison Theory?
Liquid and Gas particles are constantly moving (and may not react)
Where collisions can only occur when:
Particles have the correct orientation + sufficient kinetic energy (Ea)
Explain this diagram + Why can’t the HBr be orientated differently?
The HBr needs to be facing the C=C for a reaction to take place
Any other orientation will result in HBr bouncing off
What is the Steric Factor and how does it effect a reaction?
Steric Factor - how the shape of a molecule effects its reaction
If a molecule is too large then it wont be able to attack species and can’t react
How and why does an increase in pressure effect rate of reaction?
Increase in pressure == increase in rate of reaction
More molecules in a given volume increasing chance of successful collisions
Which line on the graph shows an increase in concentration and why?
A since:
Increase in concentration == increase in rate of reaction
More molecules in a volume of solution
Frequency of collisions increase!
How does surface area effect rate of heterogenous reactions?
(What are heterogenous reactions?)
Increase surface Area == Increase in rate of reaction
More space for collisions to occur
(A reaction between a solid and gas / liquid)
How does this Maxwell Boltzmann graph change when temperature is increased and why?
- Decrease in curve height (More molecules have more energy)
- Curve shifts to the right (More molecules have higher kinetic energy)
How does this Maxwell Boltzmann graph change when a catalyst is present and why?
- Ea shifts to the left
- As catalysts provide an alternative pathway
- Resulting in more molecules having enough kinetic energy
How does this Maxwell Boltzmann graph change when surface area is increased and why?
- NO CHANGE
- Increasing Surface Area only increased the change of successful collisions
What are the economic benefits of using catalysts?
Allows for lower temperatures saving money
Allows for a higher rate of reaction meaning more product can be made
What are heterogenous and homogenous catalysts?
Homogenous - where the catalyst is in the same phase to the reactants
Heterogenous - where the catalyst is in a different phase to the reactants
How do heterogenous catalysts work step by step?
- Adsorption - Reactant molecules form bonds with the catalyst
- Reactant Bonds are weakened and break up Forming Radicals which then form new molecules
- Desorption - Molecules then detach from the catalyst as a product
