Rates

Question 1

What is activation energy?

Answer 1

The minimum amount of energy required for a reaction to occur

Question 2

What is an enzyme

Answer 2

A biological catalyst

Question 3

What must happen for a reaction to occur?

Answer 3

• The reacting particles (reagent) must collide
• The particles must collide with enough energy
  (activation energy)

Question 4

How can the rate of reaction increase?

Answer 4

• Concentration of a solution
• Temperature
• Particle size
• Pressure
• Catalyst or Enzyme

Question 5

How does concentration affect the rate of reaction?

Answer 5

Increasing concentration of reagents increases the rate of reaction, This is because there are more particles per unit volume. So the collision rate is higher

Question 6

How does temperature affect the rate of reaction?

Answer 6

Increasing temperature increases the rate of reaction, This is because more particles have kinetic energy so more particles have an activation energy

Question 7

How does particle size affect the rate of reaction?

Answer 7

Decreasing particle size increases the surface area, which increases the rate of reaction. This is because more of the reagent is exposed to collide. So the collision rate increases

Question 8

How does the pressure of a gas affect the rate of reaction?

Answer 8

Increasing the pressure increases the rate of reaction. This is because the distance between particles is reduced. So the collision rate increases.

Question 9

How does a catalyst affect the rate of reaction?

Answer 9

Adding a catalyst increases the rate of reaction, a catalyst allows the reaction to go by an alternative pathway where the activation energy is lower.
- Increasing the surface area of a catalyst increases the rate of reaction as well

Question 10

How can you measure the rate of reaction?

Answer 10

• Measure the volume of gas made per unit (made / time )
• Measure the loss per unit time
• Measuring the colour change, per unit time
• Measuring the increase in turbidity (cloudiness) per time

Question 11

How can you measure the increase in cloudiness?

Answer 11

Draw a cross on a paper below the reaction, As the reaction takes place more and more precipitate is made, once you can’t see the cross anymore stop the time. to ensure a fair comparison the depth of the liquid must be kept constant

Question 12

What is the danger of combustion in a flour mill?

Answer 12

• Flour particles are very small so there is a very large surface area
• If the flour combusted there would be a large explosion due to the large surface area