Kinetics Flashcards
What is kinetic or rate
How fast a reaction occurs
What is collision theory
For a reaction to occur particles must collide with an energy more than or equal to that of the activation energy
Define activation energy
Minimum energy for reaction to occur/ for succesfull collisions to occur
Describe reaction profile diagram for exorthemric reaction
Recants have more energy then prod
Change in H arrow goes down
factors affecting rate of reaction
Temp
Conc
Pressure
Catalyst
Surface area
Describe effect of temp on rate of reaction
Increased temp means increased kinetic energy of particles
So particles move faster and collide more often
Thus increased likelihood of successful collisions
What is meant by succesful collision
Collisions wiht enough energy to overcome activation energy giving a faster rate of
Describe conc effect on rate
Increased conc
Particles closer together
more particles per unit volume
More collisions
More succesfull collisions
Increase rate
how will curve on graph change with an increase in pressure
If concentration increases, the shape of the energy distribution
curves do not change (i.e. the peak is at the same energy) so
the Emp and mean energy do not change.
They curves will be higher, and the area under the curves will
be greater because there are more particles.
Describe pressure effect on rate
For gases
Same effect as conc
more particles per unit volume
So particles closer
More collisions
More sucessful collisions
what is a catalyst
Catalysts increase reaction rates without getting used up.
Explanation: They do this by providing an alternative route or mechanism with a lower
activation energy.
Describe catalyst effect on rate
Increases rate of reaction
Catalyst provides alternative energy pathway for the reaction with a lower activation energy
describe effect of increased surface area on rate of reaction
Increasing surface area will cause successful collisions to occur more frequently between the
reactant particles and this increases the rate of the reaction.
if you double concentration what happens to rate
double in rate
double number of particles per unit volume
double freq of sucessful collisons
Define rate of reaction
Change in conc of a substance over a unit time
What does it show when a graph levels off
No more gas is produced
Gradient = rate - Rate is 0
what does the peak of the maxwell boltzman curve represent
most propable energy
what does area under graph on maxwell boltzman show
total number of particles present
what does the line on the right of the peak show
mean average energy
how would total area under graph change on mb graph at a higher temp
The total area under the curve should remain constant
because the total number of particles is constant
more succ coll bc more partivles met activation energt
Where does curve start and end on maxwells - Boltzman distribution
Starts at origin
Ends just above x axis (representing energy)
Y axis on maxwell boltsnan represents
Number of particles
At a higher temp describe mb curve
Moves to the right - more particles at higher energy level
Most probable energy has increased
Lower and wider peak - area under curve must stay the same
At a lower temp mb curve…
Higher peak - a large number of particles have low energy
Moves to the left
Increased pressure effect on mb curve
Area under curve increases
Msot prob energy stays the same but more particles have it
So higher peak
Marking points for shifting equilibrium
Name change
Say forward or backward reac
If its endo or exo
Say if equilibrium shifts left or right to oppose or counteract a change in the system.
Pressure increases yield bc …
Increases rate of reaction
More particles in a given volume
So increased collision frequency
Give the meaning of the term dynamic in terms of dynamic equilibrium
Both forward and reverse reaction occur at the same time
Give the meaning of the term dynamic in terms of dynamic equilibrium
Both forward and reverse reaction occur at the same time
Explain the process that causes some molecules in a sample to have very low energies (2)
Collisions (1)
Cause some molecules to slow down or lose energy (1)
Explain the process that causes some molecules in a sample to have very low energies (2)
Collisions (1)
Cause some molecules to slow down or lose energy (1)
What line on maxwell bolzman dist represents the mean energy of the molecules
Line furthest to the right
Just after the peak of the graph
Describe how a maxwell Boltzman curve looks at higher temp
Lower and to the right
crosses other graph once
Starts at origin
What is the effect of an increase in temperature on the rate of a chemical reaction - explain your answer with reference on the rate of Chemical reaction
Rate of reaction) increases
1
(At a higher temperature) more molecules/particles
1
have the minimum energy needed to react/have activation
energy/have successful collisions
What is the effect of the addition of a catalyst on the rate of chemical reaction explain your answer w reference to Maxwell boltzman dist
Rate of reaction increases
Lowers activation energy by providing alt energy pathway w lower act
So that more molecules are able to react
Explain why a small increase in temp has a large effect on the initial rate of a reaction
Much more collisions with activation energy
