Rates of Reaction + Factors Affecting + Catalysts

Question 1

Describe the collision theory

Answer 1

the only way for chemical reactions to take place is if the reactant particles collide with sufficient amount of energy to react

Question 2

Successful Collision -

Answer 2

a collision that leads to a reaction as particles have E >Ea

Question 3

2 main Factors the rate of chemical reactions depend on

Answer 3

1. Collision Frequency of reacting particles - how many collision between particles in a certain amount of time
   - more collisions = faster the reaction (because more successful collision)
2. Amount of energy particles have : more energy = more energy transferred during collision
   - more successful collisions

Question 4

Name 4 Factors the affect the rate of reaction

Answer 4

• temperature
• concentration of solution / pressure of gas
• surface area
• presence of a catalyst

Question 5

How does temperature affect the rate of reaction?

Answer 5

• Heat = particle have more energy
• move faster
• more frequent collisions
• higher temperature = increase energy of the collisions —> particles are faster+ more particles with E>Ea
• more successful collisions
• rate increases

Question 6

How does concentration (solutions) / Pressure (gas) affect the rate of reaction?

Answer 6

-higher collision frequency
- More particles in a given volume
- More frequent collisions, more crowded
- more successful collsions
rate increases

Question 7

How does having a smaller solid particle (surface area) affect the rate of reaction?

Answer 7

• More particles exposed: increase its surface area to volume ratio
• more frequent collsions -> particles have more area to work on
• more successful collisions
• rate increases

Question 8

How does a catalyst work and how does it affect the rate of reaction?

Answer 8

• provides an alternative reaction pathway for reaction with a lower activation energy
• more particles have at least the minimum amount of energy (activation energy) needed for particles to collide
• more successful collisions as more particles with E>Ea

Question 9

What is a catalyst

Answer 9

• substance that increases the rate of a chemical reaction cwithout being chemically changed or used up

Question 10

Rate of reaction equation =

Answer 10

Rate of reaction = Amount of reactant used or amount of product formed (cm^3)/ Time(s)

Question 11

What is Activation energy and why is it needed for a reaction?

Answer 11

• minimum amount of energy particles need to react with
• particles need this much energy to break the bonds in reactants to start reaction

Question 12

What happens to the energy needed if the activation energy is greater? How will it be supplied

Answer 12

greater the activation energy = more energy needed to start reaction
- need to be Supplied, e.g. heating the reaction mixture

Question 13

What are reaction profiles used for?

Answer 13

To compare the activation energy of a reaction with and without a catalyst

Question 14

Is the highest point on the curve on a reaction graph with or without a catalyst

Answer 14

Highest point = with catalyst
Lower = without catalyst