What's the collision theory?
For a reaction to occur:
Particles must collide
Particles must collide in correct orientation
Particles must collide with sufficient energy (energy greater than Ea)
What's activation energy?
Minimum energy required for a reaction to occur
According to collision theory, to increase the rate of reaction you need …
More frequent collisions - increase particles speed or have more particles present
More successful collisions - give particles more energy or lower the activation energy
What factors affect the rate of reaction?
Temperature
Concentration
S.A
Catalyst
Pressure
How does increasing the temperature affect the rate of reaction?
↑temp = ↑ROR
↑temp = ↑averge KE of the particles
More particles collide with energy greater than Ea
Frequency of successful collisions increases
How does increasing the concentration affect the rate of reaction?
Increasing conc increases rate of reaction. Increasing conc means there are more particles in a given volume therefore will be more frequent successful collisions
How does increasing the S.A affect the rate of reaction?
Increasing S.A increases rate of reaction as more particles exposed for other reactants to collide with so will be more frequent successful collisions
How would you increase the S.A of a substance?
Breaking the solid into smaller pieces
How does a catalyst affect the rate of reaction?
Substance which increases rate of reaction by creating alternative pathway without being used up or chemically changed. Lowers Ea so more particles will collide with E≥Ea so father ROR
What does the areas under maxwell-boltzmanns distribution curve show?
Area under curve is equal to the total number of molecules
Why does the MB curve start at the origin?
As no molecules have 0 energy
What does the peak represent on a MB curve?
Most probable energy
Where is the mean found on the MB curve?
Right of peak
Why does the MB curve never touch the x axis?
No upper limit to energy
How does the MB curve change at a higher temp?
Peak lower and to right
Broader peak
Therefore more molecules have E≥Ea
How does MB curve change at lower temp?
Peak higher and to left
Peak narrower
Therefore fewer have E≥Ea
What goes on the X and y axis of a MB curve?
X axis - energy
Y axis - no of molecules
How does MB curve change with increasing concentration?
Curve moves up therefore more have E≥Ea
How does the MB curve change with an inert gas?
No change
Last changeda year ago