1.5 kinetics Flashcards
what does collision theory state
for a reaction to start :
- particles must collide with each other in correct orientation
- with sufficient energy
what is meant by collision frequency
- number of collisions per unit time
how does collision theory affect reaction rate
when more collisions per unit time occur, more particles with energy => Ea increases
increasing reac rate
what is activation energy
minimum amount of energy required for reaction to take place
why does Ea tend to be greater for endothermic reactions?
reactants in lower energy level state require smore energy to reach same transition point
how do you measure rate of reaction?
- change in amount of reactant or product / time
moldm^-3s^-1
why does the maxwell boltzman curve start at origin
no particles have zero energy
what is meant by most probable energy
energy most particles have
what happens if temp increases on maxwell boltzman curve
peak gets lower and shifts right
curve spreads out
more particles have energy >= Ea
reaction rate increases
what happens to maxwell boltzman curve if temp lowers
- higher peak shifts left
- curve narrows
- less particles energy =< Ea
- reaction rate decreases
what happens to curve if a catalyst used
no change to curve shape
Ea line moves to the left
more particles energy >= Ea
how does increasing temp increase rate of reaction
- higher temps particles move faster so collide more frequently
- a higher number of collisions means a higher number of successfull collisions
- higher temps, higher proportion of molecules with energy => Ea
how does increasing concentration affect reaction rate
- higher concentration means more particles per unit volume
- particles closer together so more frequent successful collisions
- more collisions w energy >= Ea
how does increasing pressure aftect reaction rate
- higher pressure = gas particles closer
- more particles per unit volume
- more frequent and successful collisions
rate increases
