Rates of Reaction

Question 1

What is a rate?

Answer 1

measure of how fast a reaction occurs

Question 2

Rate =

Answer 2

           time

Question 3

What must reactants do in order for a reaction to take place?

Answer 3

they must collide

Question 4

What is the name of the type of energy needed for colliding particles to react?

Answer 4

activation energy

Question 5

What are the type of collisions that have the required activation energy?

Answer 5

successful collisions

Question 6

In order to increase rate, what must happen to the frequency?

Answer 6

the fequency of successful collisoins must increase too

Question 7

Name three methods of measuring a rate of reaction

Answer 7

• precipitation
• measuring volume of gas given off
• change in mass

Question 8

How does the precipitation method work?

Answer 8

• place a marker on paper and put flask with two solutions in
• time how long it takes for mark to disappear as precipitate forms

Question 9

How does measuring volume of gas method work?

Answer 9

• use gas syringe to measure how much gas is given off in regular time intervals

Question 10

How does the change in mass method work?

Answer 10

• use a mass balance

- as gas is releases, mass will decrease and when reaction finishes, the new mass will remain constant

Question 11

Name four factors which affect the rate of reaction

Answer 11

• temperature
• concentration/ pressure
• surface area
• catalyst

Question 12

How does a higher temperature affect the rate of reaction?

Answer 12

• particles have more kinetic energy
• move faster
• higher frequency of successful collisions
• faster rate of reaction

Question 13

How does a higher concentration affect the rate of reaction?

Answer 13

• more particles in a set volume
• higher frequency of successful collisions
• faster rate of reaction

Question 14

How does a higher pressure affect the rate of reaction?

Answer 14

• more particles in a set volume
• higher frequency of successful collisions
• faster rate of reaction

Question 15

How does a larger surface area affect the rate of reaction?

Answer 15

• more particles available to collide
• higher frequency of successful collisions
• faster rate of reaction

Question 16

How does a catalyst affect the rate of reaction?

Answer 16

• provides an alternate pathway
• by lowering the activation energy
• increases successful collisions
• faster rate of reaction

Question 17

name two substances used to show the effect of temperature on a rate of reaction

Answer 17

• sodium thiosulfate
• hydrochloric acid
  (two colourless solutions form yellow precipitate)

Question 18

name two substances used to show the effect of concentration on a rate of reaction

Answer 18

• hydrochloric acid
• magnesium metal
  (mass loss)

Question 19

name two substances used to show the effect of surface area on a rate of reaction

Answer 19

• hydrochloric acid
• marble chips (calcium carbonate)
  (gas syringe - volume of gas)

Question 20

what type of reaction can be used to show the effect of a catalyst on a rate of reaction?

Answer 20

decomposition reaction of hydrogen peroxide

• using catalyst of manganese oxide
• breaks down into water and oxygen