Kinetics

Question 1

What is required for a reaction to occur?

Answer 1

Particles must collide in the correct orientation with enough energy to start breaking the chemical bonds.

Question 2

What happens if the particles don’t collide?

Answer 2

A reaction won’t occur.

Question 3

What happens if the particles don’t have enough energy?

Answer 3

A reaction won’t occur.

Question 4

What happens if the particles don’t collide with the correct orientation?

Answer 4

A reaction won’t occur.

Question 5

What happens if you increase the concentration of the reactants?

Answer 5

The rate of reaction increases.

Question 6

Describe why increasing the concentration of the reactants increases the rate of reaction.

Answer 6

At a higher concentration, there are more reactant particles in the same volume. Because the reactant particles are closer together, there is an increased frequency of collisions. This increases the rate of reaction.

Question 7

What happens if we increase the pressure of gas?

Answer 7

The rate of reaction increases.

Question 8

Describe why increasing the pressure of gas increases the rate of reaction.

Answer 8

Increasing the pressure makes the particles closer together. This increases the frequency of collisions. Thus rate of reaction is increased.

Question 9

How much energy is required for a reaction to occur?

Answer 9

Energy must be equal to or greater than the activation energy.

Question 10

What occurs in the Maxwell Boltzmann Distribution?

Answer 10

Energies are distributed.

Question 11

What is on the X axis of the Maxwell Boltzmann Distribution?

Answer 11

Kinetic energy.

Question 12

What is on the Y axis of the Maxwell Boltzmann Distribution?

Answer 12

Number of Molecules

Question 13

What is the line touching the peak of the curve in the Maxwell Boltzmann Distribution?

Answer 13

The most probable energy.

Question 14

What is the line in the middle of the Maxwell Boltzmann Distribution curve?

Answer 14

The mean energy.

Question 15

What is the line near the end of the MBD curve?

Answer 15

The activation energy.

Question 16

What happens to the MBD if you change the reaction conditions?

Answer 16

The shape of the curve is altered so that the number of particles with energy greater than the activation energy is different.

Question 17

What does the total area under the curve represent?

Answer 17

The total number of molecules in the sample thus it must remain constant.

Question 18

What is the activation energy?

Answer 18

The minimum energy which particles need to collide to start a reaction.

Question 19

Effect of temperature on the rate of reaction?

Answer 19

When a substance is heated, thermal energy is transferred to it. This energy is converted to KE. The molecules of the substance will move faster and further. Increased movement means more collisions can occur with greater energy.

Question 20

Simple effect of temperature on the rate of reaction.

Answer 20

Increased temp = increased rate of reaction.

Question 21

Effect of temperature on the MBD?

Answer 21

Shifts to the right so that a greater proportion of molecules have energy greater than or equal to the Ea.

Question 22

Simple effect of increasing concentration/gas pressure on the rate of reaction?

Answer 22

Increased rate of reaction.

Question 23

Effect of increasing concentration/gas pressure on the MBD?

Answer 23

Shifts to the right.

Question 24

What is a catalyst?

Answer 24

A substance that increases the ror without being used up in the reaction.

Question 25

How does a catalyst work?

Answer 25

Provides an alternative reaction path that requires a lower activation energy for the reaction to occur.

Question 26

Effect of a catalyst on the MBD?

Answer 26

Unchanged in shape but the position of the Ea is shifted to the left.

Question 27

Why is the position of the Ea shifted to the left due to the effect of a catalyst?

Answer 27

So that a greater proportion of molecules have sufficient energy to react.