Chapter 5.2 The Maxwell Boltzmann Distribution

Question 1

Explain what maxwell Boltzmann distribution tells us (3)

Answer 1

It tells us about the distribution of energy amongst the particles,
No particles have zero energy,
Most particles have intermediate energies,
A few have very high energies,
Average energy is not the same as probable emergy

Question 2

How to find the number of particles with enough energy to react ?

Answer 2

If Ea is marked on the maxwell Boltzmann graph, the area under the graph to the right of Ea represents the number of particles with enough energy to react

Question 3

How does temperature effect the maxwell Boltzmann graph ?

Answer 3

At higher temperature the peak of the curve is lower and moves to the right, the number of particles with v high energy increases

Question 4

Why is the total area under the graph same for each temperature ? (1)

Answer 4

Because it represents the total number of particles

Question 5

What does the maxwell Boltzmann graph tell us at higher temperature ?

Answer 5

The graphs show that at higher temperatures more of the molecules have energy greater than activation energy so a higher percentage of collisions will result in reaction. This is why reaction rates increase with temperature. In fact, a small increase in temperature produces a large increase in the number of particles with energy greater than Activation energy

Question 6

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

Answer 6

Collisions causes some molecules to slow down or lose energy

Question 7

In the maxwell Boltzmann distribution, what does the area under the graph represent ?

Answer 7

• the total number of particles

Question 8

With reference to the Maxwell–Boltzmann distribution, explain why an increase in temperature increases the rate of a chemical reaction (2)

Answer 8

• more molecules have energy greater than the activation energy,
• hence rate of successive collisions increase

Question 9

State how, if at all, the value of the most probable energy (Emp) changes as the total number of molecules is increased at constant temperature (1)

Answer 9

Stays the same

Question 10

State how, if at all, the number of molecules with the most probable energy changes as the temperature is decreased without changing the total number of molecules (1)

Answer 10

Increases

Question 11

State how, if at all, the number of molecules with energy greater than the activation energy changes as the temperature is increased without c hanging the total number of molecules. (1)

Answer 11

Increases

Question 12

State why the curve at the maxwell Boltzmann distribution starts at the origin (1)

Answer 12

There are particles with zero energy

Question 13

With reference to the Maxwell–Boltzmann distribution, explain why a decrease in temperature decreases the rate of decomposition of this gas (2)

Answer 13

• decrease in the number of particles with energy greater than the activation energy,
• therefore there are less successive collisions per unit time

Question 14

Suggest why a small increase in temperature can lead to a large increase in the reaction rate between colliding particles (2)

Answer 14

Many more molecules have energy greater than the activation energy

Question 15

Label the axes on the Maxwell Boltzmann graph

Answer 15

Y axis = number of molecules

X axis = molecular energy