Topic 4- Rates of Reaction

Question 1

The decomposition of hydrogen peroxide is catalysed by adding a small amount of manganese oxide. How will the graph of the reaction of the catalyst look like?

Answer 1

The graph will be a straight line/ horizontal because a catalyst doesn’t get used up.

Question 2

In terms of the behaviour of particles, the effect of changing temperature and the effect of changing the concentration of a solution.

Answer 2

the temperature will give the particles more energy. They will also move faster and have more frequent and more energetic collisions.

Question 3

How do you find the rate of reaction using a gradient?

Answer 3

Change in Y/ Change in X

Question 4

Why are catalysts important?

Answer 4

+Reactions are quicker +They happen at lower temperatures +So it is cheaper to make a product

Question 5

What is an endothermic reaction?

Answer 5

A reaction that takes in energy from the surroundings.

Shown by a fall in temperature of the surroundings.

Question 6

What is an exothermic reaction?

Answer 6

A reaction which give out energy to surroundings.

Shown by a rise in temperature of the surroundings.

Question 7

Why does increasing pressure of a gas increase the rate of reaction?

Answer 7

The higher the pressure the faster the reaction.
Particles are closer together in a decreased volume
So there there would be more frequent collisions.

Question 8

What does a catalyst do to the activation energy?

Answer 8

The catalyst lowers the activation energy. + this means many more collisions are likely to be successful.

Question 9

What is an anomalous result?

Answer 9

+Does not fit on best line of fit +Higher or lower than expected

Question 10

What is a catalyst?

Answer 10

+A substance that speeds up chemical reactions without getting used up in the process or being chemically changed.

Question 11

What is the rate of reaction?

Answer 11

How fast a reaction takes place.

Question 12

How do you find the rate of a chemical reaction?

Answer 12

The amount of product made or the amount of reactant used up

Question 13

What is activation energy

Answer 13

The minimum amount of energy required to start a reaction

Question 14

What are the five factors affecting a reaction

Answer 14

• Concentration
• Temperature
• Catalyst
• Surface area
• Pressure (gases)

Question 15

What does a higher concentration do to a reaction?

Answer 15

• More collisions
• More successful collisions
• More frequent collisions
• Faster rate of reaction

Question 16

Why don’t all collisions between particles result in a chemical reaction?

Answer 16

Because sometimes they don’t have enough energy e.g heat

Question 17

What effect does surface area have on the rate of reaction

Answer 17

• The particles are more exposed to the solution
• More area to react on

Therefore the frequency of collision increases resulting in increase of successful collisions

Question 18

What is a catalyst and what effect does it have on the rate of a reaction

Answer 18

A catalyst will speed up the rate of a reaction by lowering the activation energy, it gives an alternative pathway for the particles to react on and it doesn’t get used up in a reaction

Question 19

What increases the rate of reaction

Answer 19

Increasing the concentration of the reactant

Question 20

What increases the rate of reaction of a solid

Answer 20

Increasing its surface area

Question 21

What happens when the reactant has smaller particles

Answer 21

The rate of reaction increases

Question 22

What happens when you increase the temperature

Answer 22

The rate of reaction increases