P2 - 6.2 Factors Affecting Rates of Reaction & Collision Theory

Question 1

What are the 4 main factors that affect the rate of chemical reactions

Answer 1

• temperature
• concentration/pressure
• surface area
• presence/absence of catalyst

Question 2

What is collision theory

Answer 2

For particles to react they have to collide with each other with sufficient energy (activation energy)

Question 3

In collision theory what is another way of saying sufficient energy

Answer 3

Activation energy

Question 4

What happens if chemicals collide with less energy than activation/sufficient energy

Answer 4

Nothing will happen because there is not enough energy

Question 5

What is activation energy

Answer 5

The minimum amount energy required for a chemical reaction to take place

Question 6

What will the rate of reaction depend on in collision theory

Answer 6

1) amount of energy particles have
2) frequency of collisions

Question 7

How does the amount of energy particles have affect the rate of reaction in collision theory

Answer 7

If particles have more energy it will mean they can move faster and transfer quicker during the collisions

Question 8

How does the frequency of collisions effect the rate of reaction in collision theory

Answer 8

Not all collisions are successful however the more they collide the more successful collisions become

Question 9

True or False: particles dont always reach activation energy

Answer 9

True

Question 10

True or False: the more particles collide, the less successful they become

Answer 10

False
The more often particles collide, the more successful collisions will become

Question 11

How does collision theory have an effect on the rate of reaction

Answer 11

They can increase the rate of reaction by having more successful collisions

Question 12

If temperature is increased, how will this effect the rate of reaction

Answer 12

• Particles gain more energy causing them to move faster
• This causes them to collide more frequently and with more energy each time increasing chances of exceeding activation energy

Question 13

What does concentration/pressure refer to

Answer 13

How many particles there are per unit of volume

Question 14

What state does concentration usually link to

Answer 14

Solutions/liquids

Question 15

What state does pressure usually link to

Answer 15

Gases

Question 16

If concentration/pressure is increased, how will this effect the rate of reaction

Answer 16

• more particles per unit of volume causes collisions to be more frequent increasing rate of reaction

Question 17

If surface area is increased, how will this effect the rate of reaction

Answer 17

• increasing the surface area allows for more reactions to take place on it causing frequency of collisions to be higher

Question 18

Which of these has the highest surface area: volume ratio
- Solid block
- Small Chunks
- Powder

Answer 18

Powder has the highest surface area: volume ratio and would increase frequency of collisions the most

Question 19

If a catalyst is used, how will this effect the rate of reaction

Answer 19

• a catalyst will lower the activation energy increasing the frequency of successful collisions

Question 20

What is a catalyst

Answer 20

A substance that speeds up a reaction without being used up in the reaction themselves

Question 21

Draw and label a reaction profile

Answer 21

Graph:
Energy along y axis
Progress of reaction along x axis
Reactants line above products line
Curve attaching the product and reactant line
Activation energy (bit above top of line to reactants)
Overall activation energy (fully from reactants to products)

Question 22

What are the most commonly used catalysts

Answer 22

Transition metals such as cobalt and nickel

Question 23

Which 2 elements are most used as catalysts

Answer 23

Cobalt and nickel

Question 24

What are we wanting to happen when increasing temperature, concentration/pressure, surface are and catalysts

Answer 24

We want a higher rate of reaction