Chemistry (Factors affecting Rate of Reaction)

Question 1

What does the reaction rate depend on?

Answer 1

Nature of the reactants.

Question 2

Increasing the concentration of reactants…

Answer 2

Increases rate of reaction.

Question 3

Increasing the pressure and decreasing volume is equivalent to…, and therefore…

Answer 3

increasing the concentration, and therefore increases the rate of reaction.

Question 4

Closer particles…

Answer 4

Causes more frequent collisions

Question 5

More frequent collisions means…

Answer 5

the proportion of particles can react together.

Question 6

Increasing the surface area…

Answer 6

Increases the number of reactant particles available for collisions.

Question 7

Increasing the surface area increases… which therefore increases..

Answer 7

Increases collisions, therefore increasing rate of reaction.

Question 8

Creating movement in a fluid is called?

Answer 8

Agitation

Question 9

Agitation decreases/increases collisions?

Answer 9

(Increases) Particles are more exposed for collisions but they are given more kinetic energy.

Question 10

A greater proportion of particles that have been agitated are given more… therefore have energy…

Answer 10

Given more kinetic energy and therefore have greater energy than the activation energy.

Question 11

An increase in temperature…

Answer 11

Increases the rate of a chemical reaction.

Question 12

When a substance gets hot its particles… and have more…

Answer 12

Particles vibrate and have more kinetic energy.

Question 13

Increase in KE causes particles to

Answer 13

Move faster and have more frequent collisions.

Question 14

A greater proportion of particles that have been increased in temperature are given more… therefore have energy…

Answer 14

Given more kinetic energy and therefore have greater energy than the activation energy.

Question 15

What is a catalyst?

Answer 15

Something that can speed up or slow down a chemical reaction.

Question 16

A positive catalyst …. reaction rate

Answer 16

Increases

Question 17

A negative catalyst … reaction rate

Answer 17

Decreases

Question 18

Catalysts increase reaction rate by …. that has a …..

Answer 18

providing an alternate reaction pathway that has a lower activation energy.

Question 19

A greater proportion of particles that have been catalysed are given more… therefore have energy…

Answer 19

Have a more sufficient energy and therefore have enough energy to overcome the activation energy.

Question 20

Describe the effect that catalysts have on the hill part of an energy profile diagram.

Answer 20

The hill of the energy profile diagram moves down if the reaction is catalysed. This provides an alternate reaction pathway which is why the activation energy is lower.

Question 21

Explain, using collision theory, why an increase in temperature can result in an increase in rate of reaction?

Answer 21

• Energy increase means the energy becomes greater than the activation energy.
• Kinetic energy in particles increase
• Movement and vibration increase causes more collisions
• Increase in collisions increases the rate of reaction

Question 22

Explain, using collision theory, why diluting a solution can result in a reduction in rate of reaction?

Answer 22

• Concentration decreases
• Increase difficulty in particles to collide, meaning less collisions
• Further apart, less collisions means less reactant particles
• Decreases in particles colliding with less collisions in the correct orientation.

Question 23

Explain, using collision theory, why grinding a soil sample to a small particle size can result in an increase in rate of reaction?

Answer 23

• Increase in surface area
• Increase in the reactant particles
• Increase in likelihood of collisions with correct orientation.

Question 24

Explain, using collision theory, why the introduction of an inert gas (such as nitrogen) into a closed (sealed) chemical system can result in an increase in rate of reaction?

Answer 24

• Introduction of a gas in a closed system increases pressure
• Increase in pressure decreases volume
• Decrease in volume allows a higher chance of collisions with the reactant particles.
  Increase in collisions increases the reaction rate.

Question 25

Explain, using collision theory, why the addition of a catalyst into a reaction mixture can result in an increase in rate of reaction?

Answer 25

• Catalysts provide an alternate reaction pathway giving an alternate lower required activation energy.
• This increases the proportion of particles that have sufficient energy to react.
• Sufficient energy means that the particles have greater energy than the activation energy
• This will increase the likelihood of collisions increasing the rate of reaction.