kinetics Flashcards
what is collision theory?
for a chemical reaction to occur, reactants must:
- Physically collide in the right direction
- Have a sufficient energy to react (Ea)
conditions needed to increase rate of reaction?
Increasing the frequency of collisions
Increase energy of reactants
Lowering Ea
4 methods to increase the rate
Increasing conc/pressure
↑ No. of reactant molecules/↓ space
↑ frequency of collisions(+ pressure)
Increasing surface area
↑ reactant exposed
↑ frequency of collisions
Increasing the temperature
Reactant molecules gain ke
More have enough Ea
↑ frequency of collisions
Catalyst
Lowers Eact
More molecules have enough e to react
what does the arrow point to?
modal of energy that particles have
where are the particles that sufficient energy to react
after the Ea line
where is the average energy that pariticles have?
to the right of the modal line
label the axis
x = energy
y = amount of particles
why does the graph start at (0,0)
no particles have no energy
how do u finish the graph
never reaches the x-axis
what is this?
maxwell-boltzmann curve
sgows the amount of energy of particles in a gas
what would a higher conc/ pressure do to change the curve?
curve shifts up
area increases as more particles in less space
what would a catalyst do to the curve
doesn’t change curve.
Ea line drawn again as Ecat.
what would a change in temperature do to change the graph?
lower temp= shift to left and taller
higher temp= shift to right and longer
two types of catalyst
heterogeneous
homogeneous
what is a catalyst
increases the reaction rate by providing on the alternative route for the reaction that has a lower activation energy
homogenous catalyst?
catalyst in same state as the reactant eg aqueous catalyst
heterogeneous catalyst?
catalyst in a different state to the reactant eg solid catalyst
pros of a catalyst
increased rate at lower temperatures/pressure therefore less energy needed
lower economic and environmental cost(emissions)
show a reaction profile of an exothermic reaction with a catalyst
