4.3 Rates

Question 1

How does increasing temperature increase rate of reaction?

Answer 1

particles gain more kinetic energy

Question 2

How does increasing concentration increase rate of reaction?

Answer 2

more particles in the same volume

Question 3

How does reducing particle size increase the rate of reaction?

Answer 3

increases surface area
more contact between reactants

Question 4

How does using a catalyst increase the rate of reaction?

Answer 4

reduces activation energy, provides alternative path

Question 5

How does changing pressure increase rate of reaction?

Answer 5

same particles in smaller volume

Question 6

What is collision theory?

Answer 6

particles must collide with required energy (activation energy) for the reaction

Question 7

What is activation energy?

Answer 7

amount of energy particles need to react

Question 8

What is collision frequency?

Answer 8

how often particles collide with each other

Question 9

What is percentage success?

Answer 9

what percentage of collisions have enough energy

Question 10

What factors affect rate of reaction?

Answer 10

pressure
concentration
surface area
catalyst
temperature

Question 11

What factors affect collision frequency?

Answer 11

concentration
pressure
surface area

Question 12

What factors affect percentage success?

Answer 12

temperature
catalyst

Question 13

Name an experiment to measure the effect of surface area on rate

Answer 13

marble chip experiment

Question 14

Name an experiment to measure the effect of temperature on rate

Answer 14

magnesium and acid experiment

Question 15

Name an experiment to measure the effect of catalyst on rate

Answer 15

hydrogen peroxide experiment

Question 16

Why are catalysts not included in the equation?

Answer 16

because they are unchanged in the reaction

Question 17

Which catalyst is used in the hydrogen peroxide experiment?

Answer 17

manganese oxide

Question 18

How is the scientist able to retrieve the catalyst?

Answer 18

it is not used up in the reaction

Question 19

What is a catalyst?

Answer 19

substance that increases rate of reaction but remains chemically unchanged

Question 20

How do catalysts work?

Answer 20

provide an alternative pathway
percentage of collisions with enough energy is higher
more successful collisions

Question 21

Name an experiment that can demonstrate the effect of concentration on rate

Answer 21

disappearing cross experiment

Question 22

What is the disappearing cross experiment?

Answer 22

react sodium thiosulphate
solution with hydrochloric acid

Question 23

In the disappearing cross experiment, which solid is produced?

Answer 23

sulphur

Question 24

What is the equation for the disappearing cross experiment?

Answer 24

sodium thiosulphate + hydrochloric acid -> sulphur + water + sulphur dioxide

Question 25

In the disappearing cross experiment, what is the independent variable?

Answer 25

concentration of sodium thiosulphate

Question 26

In the disappearing cross experiment, what is the dependent variable?

Answer 26

time taken for cross to disappear

Question 27

In the disappearing cross experiment, what are the control variables?

Answer 27

volume of solution concentration of HCl temperature

Question 28

What does the disappearing cross experiment prove?

Answer 28

rate is proportional to concentration

Question 29

What is the magnesium and acid experiment?

Answer 29

reacting magnesium with hydrochloric acid

Question 30

Why does the cross disappear in the disappearing cross experiment?

Answer 30

sulphur is produced in suspension - makes solution cloudy so cross is not visible under breaker anymore

Question 31

In the magnesium and acid experiment, what is the independent variable?

Answer 31

temperature of HCl

Question 32

In the magnesium and acid experiment, what is the dependent variable?

Answer 32

time take for Mg to disappear

Question 33

In the magnesium and acid experiment, what are the control variables?

Answer 33

mass and surface area of Mg volume and concentration of HCl

Question 34

What is the equation for the magnesium and acid experiment?

Answer 34

magnesium + hydrochloric acid -> magnesium chloride + hydrogen

Question 35

What does the magnesium and acid experiment prove?

Answer 35

temperature is not proportional to rate

Question 36

What is the equation for rate of a reaction?

Answer 36

rate = collision frequency x percentage success

Question 37

What is the hydrogen peroxide experiment?

Answer 37

hydrogen peroxide broken down into water and oxygen

Question 38

What is the equation for the hydrogen peroxide experiment?

Answer 38

hydrogen peroxide -> water + oxygen catalysed by manganese oxide

Question 39

In the hydrogen peroxide experiment what is the independent variable?

Answer 39

catalyst being used

Question 40

In the hydrogen peroxide experiment what is the dependent variable?

Answer 40

volume of oxygen produced

Question 41

What are the control variables in the hydrogen peroxide experiment?

Answer 41

volume and concentration of hydrogen peroxide temperature mass and surface area of catalyst

Question 42

What does the hydrogen peroxide experiment prove about rate?

Answer 42

catalyst increases rate