Unit 3.2.2 - Kinetics

Question 1

Do particles react every time they collide?

Answer 1

No

Question 2

What does the collision theory state?

Answer 2

A reaction will only take place between two particles if they collide in the right direction and with a sufficient amount of energy

Question 3

What is the activation energy?

Answer 3

The minimum amount of kinetic energy particles need to react

Question 4

Why do particles need a minimum amount of energy to react?

Answer 4

It is the amount of energy needed to break the bonds in the products

Question 5

What are the two definitions of the rate of reaction?

Answer 5

The decrease in concentration of the reactants per unit of time
The increase in concentration of the products per unit of time

Question 6

What is the Maxwell-Boltzman distribution?

Answer 6

A model that shows the kinetic energy of molecules and how many molecules have that particular kinetic energy

Question 7

Sketch the Maxwell-Boltzman distribution?

Answer 7

See flash card

Question 8

Why does the Maxwell-Boltzman distribution curve start at the origin?

Answer 8

Because no molecules will have zero energy

Question 9

What does the peak of the Maxwell-Boltzman distribution show?

Answer 9

The most likely energy of the molecules

Question 10

Why does the Maxwell-Boltzman distribution never reach the x axis again?

Answer 10

Because theoretically a particle can have an infinite amount of energy

Question 11

Which line do the particles have to be past in the Maxwell-Boltzman distribution in order to react when they collide?

Answer 11

The activation line

Question 12

How does an increase in temperature increase the rate of reaction?

Answer 12

When you increase the temperature the molecules have more kinetic energy and are moving faster and so increasing the collision frequency
The increase in temperature and kinetic energy also means the collision energy of the molecules increase
With more collisions and the molecules having more energy the number of successful collision increase and so does the rate of reaction

Question 13

If they ask you to refer to the Maxwell-Boltzman distribution as to why an increases in temperature increases the rate of reaction what should you say?

Answer 13

As the particles have more energy a greater amount of the particles will have the activation energy and so increasing the amount of successful collision

Question 14

Sketch how increasing the temperature affects the Maxwell-Boltzman distribution?

Answer 14

See flash card

Question 15

Why is the area under the Maxwell-Boltzman distribution curve the same when you increase the temperature?

Answer 15

The total number of molecular is still the same

Question 16

Does a small temperature increase lead to a small or large increase in the rate of reaction?

Answer 16

Large

Question 17

Why does increasing the concentration of reactants in a solution or the pressure in a gas increase the rate of reaction?

Answer 17

The molecules on average will be closer together, this means there is an increased collision frequency and so the number of successful collisions increase, increasing the rate of reaction

Question 18

What is a catalyst?

Answer 18

A substance which increases the rate of reaction without being used up or changed

Question 19

How does a catalyst work?

Answer 19

It provides an alternative reaction pathway with a lower activation energy and so increasing the rate of reaction

Question 20

How does a catalyst increase the rate of reaction?

Answer 20

It lowers the activation energy of a molecule and so more molecules have a collision energy greater than the activation and so the amount of successful collision increase, increasing the rate of reaction

Question 21

How does a catalyst effect the Maxwell-Boltzman distribution?

Answer 21

It moves the activation energy line to the left