Zusammenfassung der Ressource
A2 Kinetics
- Rate of Reaction: the change in concentration of reactants and products in a
reaction per unit time
- Units of Rate: moldm-3s-1
- Order of Reaction: the power to which a species is raised to in the rate equation
- 1st Order
- Rate is directly proportional to concentration of species
- 2nd Order
- Rate is directly proportional to square of species
concentration
- 0 Order
- Species has no
effect on rate
- Overall order: all the
orders in rate equation added together
- Reactions often have multiple 'steps' as there are many
ions/molecules so they are unlikely to all collide at once
- Mechanism: separate steps leading from reactants to products
- Rate Determining Step (RDS): the slowest step
in the mechanism
- Reaction is only as fast as its slowest step so the RDS determines
overall rate
- Determine K by:
- Rate / [A][B]
- A temperature increase leads to an increase in K
- For a 1st order overall reaction the unit of k is s -1
- For a 2nd order overall reaction the unit of k is mol-1dm3s -1
- For a 3rd order overall reaction the unit of
k is mol-2dm6s -1