Kinetics

Question 1

Activation Energy

Answer 1

The minimum amount of energy which molecules need to collide to start a reaction.

Question 2

5 Things dealing with Collision Theory

Answer 2

1. Temperature
2. Pressure
3. Concentration
4. Surface Area
5. Catalyst

Question 3

What is the area underneath the curve?

Answer 3

Total Number of molecules

Sometimes they reject particles, so always use molecules.

Question 4

What is C and D

Answer 4

C: Represents the most probable energy
D: Represents the mean energy as the curve is not symmetrical

Question 5

Why in the Maxwell-Distribution graph, does it start at zero?

Answer 5

This is because no particles have no energy

Thus, all particles have energy

Question 6

How does the graph shift when temperature decreases?

Answer 6

Shifts to the left

Question 7

How does the graph shift when the temperature increases?

Answer 7

It shifts to the right. The increase in kinetic energy broadens and flattens the curve due to a greater spread of values.

Question 8

What happens to the activation energy when there is an increase/decrease in temperature?

Answer 8

The activation energy does not change.
An increase in temp means that more particles can react; more kinetic energy; increase of successful collisions; many more molecules have energy greater than the activation energy.
A decrease in temp means less particles can react; less kinetic energy; decrease of successful collisions

Question 9

What is a catalyst?

Answer 9

A substance that speeds up the reaction

But is chemically unchanged at the end

Question 10

How do catalysts work?

Answer 10

It lowers the activation energy

And provides an alternative pathway for the reaction to take place

Question 11

What does the graph look like when a catalyst is introduced?

Answer 11

Question 12

What does the graph look like when concentration or pressure increases?

Answer 12

Question 13

What is the definition of rate of reaction?

Answer 13

Change in concentration of a substance in unit time

Question 14

What is the unit of rate of reaction?

Answer 14

Question 15

What does a concentration-time graph look like?

Answer 15

Question 16

Draw the experimental set-up for rates of reaction

Answer 16

Question 17

Explain the process that causes some molecules to have very low energies

Answer 17

Collisions cause some molecules to slow down or lose energy

Question 18

What is the method of increasing the proportion of successful collisions?

Answer 18

By using a catalyst - lowers the activation energy by providing another pathway for the reaction to occur and this means more particles successfully collide frequently so they have greater energy than the activation energy

Question 19

Explain what happens to the particles when increasing temp

Answer 19

The rate of reaction increases
Because more particles frequently and successfully collide due to an increase in kinetic energy
More particles have the minimum energy to collide successfully
There is a higher proportion of particles that have energy greater than the activation energy

Question 20

Explain what happens to particles when increasing concentration

Answer 20

More reactant particles in a given area in the solution
Increases the rate of reaction because more particles have a chance of successfully colliding and reacting with each other frequently