Kinetics Flashcards
what must happen for a reaction to occur
particles must collide with energy greater than or equal to activation energy E>Ea
why might a reaction occur very slowly?
a small number of particles have E>Ea
why do most collisions not cause a reaction
a small number of particles have E>Ea
why will all of the reactants eventually gain enough energy to react?
molecules gain energy due to collisions
why do some particles only have a very small amount of energy?
collisions cause molecules to slow down or lose energy
what is rate of reaction
change in concentration per unit of time
factors affecting rate of reaction
temperature
catalyst
surface area
pressure increase
concentration increase
describe the maxwell boltzman curve
- line must start at the origin as no particles can have zero energy
- peak under the curve shows most probable value for the energy of the particles
- area under the curve shows total volume of particles
- area under the curve but to the right hand side represents particles with enough energy to react E>Ea
- line never touches x axis
- mean energy of particles is a line where the area under the curve on either side of the line is equal.
drawing a curve for a higher temperature
High T peak must be to the right with a lower height
curves must only cross once
High T curve is wider and broader
The size of the shaded area is larger
(vertically)
drawing a curve at a lower temperature
The low T peak must be to the left
curve is more narrower and taller
size of shaded area is smaller for low T
how would the graph change for pressure or conc increase
the EMP and Ea would stay the same
total area under the graph would increase
a catalyst increases rate of reaction because…
the Ea decreases
more particles have energy greater that Ea
so more frequent successful collisions
