Kinetics

Question 1

What must happen in order for a chemical reaction to occur?

Answer 1

Reactants must physically collide with sufficient energy (the activation energy) to react and transfer electrons

Question 2

What must me done to increase the rate of a reaction?

Answer 2

• Increase collision frequency- Increase reactant energy- Lower the activation energy

Question 3

How can you increase the rate of an aqueous reaction?

Answer 3

Increase the concentration so that there are an increased number of reactant molecules per unit and the frequency of collisions is increased

Question 4

How can you increase the rate of a gaseous reaction?

Answer 4

Increase the pressure so that there are more reactant molecules per unit so that the frequency of collisions is increased

Question 5

How can you increase the rate of a solid reaction?

Answer 5

Increase the surface area so that more reactant is exposed and the frequency of collisions will increase

Question 6

How can increasing the temperature increase the rate of a reaction?

Answer 6

Reactant molecules will gain kinetic energy so more molecules will have the activation energy (sufficient energy to react) and the frequency of collisions will increase

Question 7

How can adding a catalyst increase the rate of a reaction?

Answer 7

The catalyst lowers the activation energy by providing an alternate reaction pathway so more molecules will have sufficient energy to react

Question 8

What does the Maxwell-Boltzmann distribution curve show?

Answer 8

The amount of energy against the fraction of reactants with energy

Question 9

Where does the mode of a Maxwell-Boltzmann distribution curve sit?

Answer 9

To the left of the mean and the activation energy

Question 10

Where does the mean on a Maxwell-Boltzmann distribution curve sit?

Answer 10

Between the mode and activation energy

Question 11

What is the area of a Maxwell-Boltzmann distribution curve?

Answer 11

The number of reactant molecules

Question 12

What is the area to the right of the activation energy?

Answer 12

Number of molecules with energy greater than the activation energy

Question 13

What happens to rate when you increase concentration?

Answer 13

Rate increases

Question 14

What happens to the Maxwell-Boltzmann distribution curve when concentration is increased?

Answer 14

• Curve shifts up- Area increases due to an increased number of reaction molecules- Increase in collision frequency- Number of particles with sufficient energy increases - Increase in number of successful collisions - Number of molecules reacting increases but proportionally remains the same

Question 15

What happens to the rate of a reaction when temperature is increased?

Answer 15

Rate is increased

Question 16

What happens to the Maxwell-Boltzmann distribution curve when temperature is increased?

Answer 16

• Curve shifts right and down- Increase in kinetic energy inbound reactant particles - Increased frequency of collisions - Increased number of particles with sufficient energy to react- Increased proportion that have sufficient energy to react

Question 17

What happens to rate of reaction when a catalyst is added?

Answer 17

Rate increases

Question 18

What do catalysts do to the Maxwell-Boltzmann distribution curve?

Answer 18

• Catalysts lower the activation energy- Cure does not change- Large number of particles now have sufficient energy - Activation energy line moves to the left

Question 19

What does a catalyst do?

Answer 19

A catalyst increases the rate of a reaction by providing an alternate route for the reaction with a lower activation energy

Question 20

What does it mean to have a lower activation energy?

Answer 20

A lower activation energy means that a greater number of particles will have have sufficient energy to react. Therefore we get more successful collisions

Question 21

What is a homogeneous catalyst?

Answer 21

A catalyst In the same state/phase as the reactants

Question 22

What is a heterogeneous catalyst?

Answer 22

A catalyst in a different state/phase as the reactants

Question 23

What are the benefits of catalysts?

Answer 23

They increase the rate of a reaction at a lower temp and pressure so less energy is needed so the economic and environmental cost is lowered