Kinetics

Question 1

What is kinetic or rate

Answer 1

How fast a reaction occurs

Question 2

What is collision theory

Answer 2

For a reaction to occur particles must collide with an energy more than or equal to that of the activation energy

Question 3

Define activation energy

Answer 3

Minimum energy for reaction to occur/ for succesfull collisions to occur

Question 4

Describe reaction profile diagram for exorthemric reaction

Answer 4

Recants have more energy then prod
Change in H arrow goes down

Question 5

factors affecting rate of reaction

Answer 5

Temp
Conc
Pressure
Catalyst
Surface area

Question 6

Describe effect of temp on rate of reaction

Answer 6

Increased temp means increased kinetic energy of particles
So particles move faster and collide more often
Thus increased likelihood of successful collisions

Question 7

What is meant by succesful collision

Answer 7

Collisions wiht enough energy to overcome activation energy giving a faster rate of

Question 8

Describe conc effect on rate

Answer 8

Increased conc
Particles closer together
more particles per unit volume
More collisions
More succesfull collisions
Increase rate

Question 9

how will curve on graph change with an increase in pressure

Answer 9

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.

Question 10

Describe pressure effect on rate

Answer 10

For gases
Same effect as conc
more particles per unit volume
So particles closer
More collisions
More sucessful collisions

Question 11

what is a catalyst

Answer 11

Catalysts increase reaction rates without getting used up.
Explanation: They do this by providing an alternative route or mechanism with a lower
activation energy.

Question 12

Describe catalyst effect on rate

Answer 12

Increases rate of reaction
Catalyst provides alternative energy pathway for the reaction with a lower activation energy

Question 13

describe effect of increased surface area on rate of reaction

Answer 13

Increasing surface area will cause successful collisions to occur more frequently between the
reactant particles and this increases the rate of the reaction.

Question 14

if you double concentration what happens to rate

Answer 14

double in rate
double number of particles per unit volume
double freq of sucessful collisons

Question 15

Define rate of reaction

Answer 15

Change in conc of a substance over a unit time

Question 16

What does it show when a graph levels off

Answer 16

No more gas is produced
Gradient = rate - Rate is 0

Question 17

what does the peak of the maxwell boltzman curve represent

Answer 17

most propable energy

Question 18

what does area under graph on maxwell boltzman show

Answer 18

total number of particles present

Question 19

what does the line on the right of the peak show

Answer 19

mean average energy

Question 20

how would total area under graph change on mb graph at a higher temp

Answer 20

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

Question 21

Where does curve start and end on maxwells - Boltzman distribution

Answer 21

Starts at origin
Ends just above x axis (representing energy)

Question 22

Y axis on maxwell boltsnan represents

Answer 22

Number of particles

Question 23

At a higher temp describe mb curve

Answer 23

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

Question 24

At a lower temp mb curve…

Answer 24

Higher peak - a large number of particles have low energy
Moves to the left

Question 25

Increased pressure effect on mb curve

Answer 25

Area under curve increases
Msot prob energy stays the same but more particles have it
So higher peak

Question 26

Marking points for shifting equilibrium

Answer 26

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.

Question 27

Pressure increases yield bc …

Answer 27

Increases rate of reaction
More particles in a given volume
So increased collision frequency

Question 28

Give the meaning of the term dynamic in terms of dynamic equilibrium

Answer 28

Both forward and reverse reaction occur at the same time

Question 29

Give the meaning of the term dynamic in terms of dynamic equilibrium

Answer 29

Both forward and reverse reaction occur at the same time

Question 30

Explain the process that causes some molecules in a sample to have very low energies (2)

Answer 30

Collisions (1)
Cause some molecules to slow down or lose energy (1)

Question 31

Explain the process that causes some molecules in a sample to have very low energies (2)

Answer 31

Collisions (1)
Cause some molecules to slow down or lose energy (1)

Question 32

What line on maxwell bolzman dist represents the mean energy of the molecules

Answer 32

Line furthest to the right
Just after the peak of the graph

Question 33

Describe how a maxwell Boltzman curve looks at higher temp

Answer 33

Lower and to the right
crosses other graph once
Starts at origin

Question 34

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

Answer 34

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

Question 35

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

Answer 35

Rate of reaction increases
Lowers activation energy by providing alt energy pathway w lower act
So that more molecules are able to react

Question 36

Explain why a small increase in temp has a large effect on the initial rate of a reaction

Answer 36

Much more collisions with activation energy