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Rates of Reactions

Question 1 of 7

1

An increase in temperature increases the rate of reaction. Why?
How many of these are correct explanations.
- The particles move faster because they have more energy.
- Particles collides more often.
- There are more particles per unit volume, resulting in more collisions.
- More of the collisions between particles are successful because they have more energy (have the activation energy).
- Rate of reaction increases because there is an increase in the frequency of collisions. /

Select one of the following:

  • 2

  • 3

  • 4

Explanation

Question 2 of 7

1

Increasing the concentration of the reactant increases the rate of the reaction. Why?
How many of these are correct explanations.
- Rate of reaction increases because the particles move faster and collide more.
- Rate of reaction increases because there are more particles per unit volume.
- Rate of reaction increases because there is an increase in the frequency of collisions.
- Rate of reaction increases because the particles have more energy.

Select one of the following:

  • 2

  • 3

  • 1

Explanation

Question 3 of 7

1

What is the effect of increasing the pressure on the rate of reaction?

Select one of the following:

  • Rate of reaction increases because particles are closer together and so the frequency of collisions increases.

  • Rate of reaction increases because there are more successful collisions.

  • Rate of reaction increases because more of the particles have the required activation energy.

Explanation

Question 4 of 7

1

Increasing the surface area of a solid reactant causes an increased rate of reaction. Why?

Select one of the following:

  • More particles are exposed to the other reactant, meaning there are more collisions, so increasing the rate of reaction.

  • The increased surface area means that the pressure of the reaction is increased, hence causing more collisions.

  • The increased surface area increases the concentration of the reactant, resulting in more collisions.

Explanation

Question 5 of 7

1

What do catalysts do?

Select one of the following:

  • Slow down the rate of reaction

  • Increase the rate of reaction

  • Activate a reaction

Explanation

Question 6 of 7

1

Why do catalysts not need replacing too often?

Select one of the following:

  • They are not used up.

  • They are unreactive.

Explanation

Question 7 of 7

1

Which two statements best explain how catalysts speed up reactions?
A) Catalysts do not get used up during the reaction.
B) Catalysts make reactions exothermic.
C) Catalysts lower the activation energy of the reaction.
D) Catalysts provide a different route for a chemical reaction to occur.
E) Catalysts raise the temperature of the reaction.

Select one of the following:

  • C and E

  • C and D

  • A and D

  • A and B

Explanation