rates of reaction (4.1)

Question 1

when can a chemical reaction only happen

Answer 1

when the reactant particles collide with enough energy

Question 2

what is the amount of energy particles need to react called

Answer 2

activation energy

Question 3

what does the overall rate of reaction spend on

Answer 3

the collision frequency
percentage success

Question 4

what is a collision frequency

Answer 4

how often do the particles collide with each other

Question 5

what is a percentage success

Answer 5

what percentage of the collisions have enough energy

Question 6

what are the four factors that effect rate of reaction

Answer 6

surface area
concentration
temperature
catalysts

Question 7

why does a higher solid surface area increase rate of reaction

Answer 7

more of the solid is exposed to the other particles
so the collision frequency is higher
so there are more successful collisions per unit time

Question 8

why does increasing temperature increase rate of reaction

Answer 8

the particles have more kinetic energy
so the percentage of collisions with enough energy is higher
so there are more successful collisions per unit time

Question 9

why does having a higher concentration/pressure increase rate of reaction

Answer 9

there are more particles per unit volume
so the collision frequency is higher
so there are more successful collisions per unit time

Question 10

why do catalysts increase rate of reaction

Answer 10

they provide an alternative route with a lower activation energy
so the percentage of collisions with enough energy is higher
so there are more successful collisions per unit time

Question 11

what experiment shows the effect of surface area with rates of reaction

Answer 11

the marble chip experiment

Question 12

what is the marble chip experiment

Answer 12

reacting calcium carbonate (marble) with hydrochloric acid

Question 13

indépendant variable of the marble chip experiment

Answer 13

sizes of CaCO3(s) chips

Question 14

dependant variable of the marble chip experiment

Answer 14

volume of CO2(g)

Question 15

control variable of marble chip experiment

Answer 15

mass of CaCO3(s)
volume and concentration of HCL(aq)
temperature

Question 16

results of marble chip experiment

Answer 16

faster beginning because the rate is increased, so the volume of CO2 is increasing faster
same final volume brace the amount of reactants hasn’t changed, so the experiment produces the same amount of CO2

Question 17

what experiment is used to show how concentration effects rate of reaction

Answer 17

disappearing cross experiment

Question 18

what is the disappearing cross experiment

Answer 18

reacting sodium thiosulphate solution with hydrochloric acid

Question 19

independent variable of disappearing cross experiment

Answer 19

concentration of the NaS2O3 (sodium thiosulphate solution)

Question 20

dependent variable of disappearing cross experiment

Answer 20

time taken for cross to disappear

Question 21

control variables for disappearing cross experiment

Answer 21

total volume of solution
concentration of HCL(aq)
temperature

Question 22

1 rate =

Answer 22

collision frequency x percentage success

Question 23

how is rate calculated in the disappearing cross experiment

Answer 23

rate = 1/time taken (s)

Question 24

what does the disappearing cross experiment show

Answer 24

rate is proportional to concentration
double the concentration = double the rate
triple the concentration = triple the rate etc

Question 25

what experiment is used to show how temperature effects rate of reaction

Answer 25

magnesium and acid experiment

Question 26

what is the magnesium and acid experiment

Answer 26

when you react magnesium(s) with hydrochloric acid(aq)

Question 27

indépendant variable for magnesium and acid experiment

Answer 27

temperature of HCL(aq)

Question 28

dependant variable for the magnesium and acid experiment

Answer 28

time taken for the Mg(s) to disappear

Question 29

control variable for the magnesium acid experiment

Answer 29

mass and surface area of MG(s) volume and concentration of HCL(aq)

Question 30

how is rate calculated in the magnesium and acid experiment

Answer 30

rate = 1/time taken (s)

Question 31

what does the magnesium acid experiment show

Answer 31

rate isn't proportional to temperature

Question 32

what are catalysts

Answer 32

substances that increase rate and remain chemically unchallenged

Question 33

how do catalysts work?

Answer 33

they provide an alternate route with a lower activation energy so the percentage of collisions with enough energy is higher so there are more successful collisions per unit time

Question 34

what experiment shows the effect of catalysts with rate of reaction

Answer 34

hydrogen peroxide experiment

Question 35

what is the hydrogen peroxide experiment

Answer 35

the decomposition of hydrogen peroxide

Question 36

what is the catalyst used in the hydrogen peroxide experiment

Answer 36

manganese(IV) oxide (mnO2)

Question 37

what does manganese oxide do in the hydrogen peroxide experiment

Answer 37

it makes a reaction that usually takes days to finish, take only a few seconds to finish

Question 38

independent variable in the hydrogen peroxide experiment

Answer 38

what catalyst is being used

Question 39

dependent variable of the hydrogen peroxide experiment

Answer 39

volume of O2

Question 40

control variables in the hydrogen peroxide experiment

Answer 40

volume and concentration of H2O2(aq) temperature mass and surface area of the catalyst

Question 41

what does the hydrogen peroxide experiment show

Answer 41

more effective catalysts increase rate more effectively