3.1.5 Kinetics

Question 1

What is collision theory?

Answer 1

-Reactions can only occur when collisions take place between particles that have sufficient energy
-Energy needed to break bonds in reactants
-Minimum energy is called activation energy

Question 2

Define activation energy

Answer 2

the minimum energy which particles need to collide to start a reaction

Question 3

What does the Maxwell-Boltzmann distribution show?

Answer 3

the spread of energies that molecules of a gas have at a particular temperature

Question 4

Draw a MB distribution curve with annotations

Answer 4

google doc

Question 5

How can a reaction go to completion if few particles have energy greater than Ea ?

Answer 5

Particles can gain energy through collisions

Question 6

Describe how the MB distribution curve will change when you increase temperature

Answer 6

-Total area should remain constant
-Molecules have a wider range of energies than at lower temperatures
-Both Emp and mean energy have higher energies

google doc

Question 7

Define rate of reaction

Answer 7

The change in concentration of a substance in unit time

Question 8

Explain how increasing concentration affect the rate of reaction. [3]

Answer 8

-More particles per unit volume
-More frequent collisions
-R.o.r increases

Question 9

How does the MB curve change if you double concentration/pressure?

Answer 9

Peak is at the same energy
Area will be doubled as there are 2x the number of particles
More particles have energy > Ea (not a greater proportion)

google doc

Question 10

What is the effect of increasing temperature on the rate of reaction?

Answer 10

-Particles have increased kinetic energy
-Many more particles have E >= Ea
-Many more successful collisions
-Significant increase in rate of reaction

Question 11

How does increasing surface area affect the rate of reaction?

Answer 11

-More particles exposed
-More frequent collisions
-R.o.r increases

Question 12

What is the definition of a catalyst?

Answer 12

Substances that increase reaction rates without getting used up

Question 13

How do catalysts work?

Answer 13

They provide an alternative route/mechanism with a lower activation energy

Question 14

Draw an energy profile diagram for an exothermic reaction with and without a catalyst

Answer 14

google doc

Question 15

Why does lowering activation energy increase the rate of reaction?

Answer 15

-more particles have energy above Ea
-higher frequency of effective collisions

GOOGLE doc

Question 16

ON GOOGLE DOC

Answer 16

1. A = 25cm^3 of 2M
2. B = 50cm^3 of 2M
3. D = 50cm^3 of 4M