Ozone

Question 1

how does sunscreen work

Answer 1

UV light is absorbed by a promoted e- then falls via thermal mechanism. Preventing uv from being absorbed by skin molecules and damaging them

Question 2

explain the origin of the photochemical smog

Answer 2

UV light creates a mixture of hydrocarbons, ozone, NO and NO2

Question 3

What were CFC’s used for?

Answer 3

CFC’s were used for refrigerants

Question 4

why are termination reactions so slow

Answer 4

because radicals are in such low concentration

Question 5

define electro negativity

Answer 5

ability of an atom to withdraw a pair of electrons from within a covalent bond

Question 6

where does NO come from

Answer 6

particle combustion of nitrogen in car engines

Question 7

where does OH come from

Answer 7

OH comes from free radical cleavage of water using uv

Question 8

what is heterolytic fission

Answer 8

produces ions

e.g. H+ and Cl-

Question 9

what is homolytic fission

Answer 9

produces radicals

eg. Br2 > Br• + Br•

Question 10

conditions of haloalkane reactions

Answer 10

UV and 300°c

Question 11

how are haloalkanes made

Answer 11

1. from alkanes by substitution
2. from alkenes by addition
3. from alcohols

Question 12

define a nucleophile

Answer 12

a molecule with a lone pair of e- that can be donated to a +vely charged atom to form a covalent bond

Question 13

common nucleophiles are

Answer 13

OH- ion
CN- ion
H2O

Question 14

how do ID - IDs work

Answer 14

the more protons (and e-) the bigger the dipole and the stronger the ID-ID forces (=higher bpt)

Question 15

where does PD-PD bonding occur

Answer 15

in polar molecules

Question 16

how strong is hydrogen bonding

Answer 16

very

Question 17

C-Cl is a more polar bond than C-I this means the C-Cl bond is…

Answer 17

stronger

Question 18

pd - pd forces stand for…

Answer 18

permanent dipole - permanent dipole

Question 19

pd - pd forces arise due to…

Answer 19

differences in atoms electronegativity in a covalent bond causing electrostatic attractions

Question 20

id - id forces stand for…

Answer 20

instantaneous dipole - induced dipole

Question 21

id - id forces arise due to…

Answer 21

uneven distributions of electrons creating temporary dipoles that induce dipoles in their neighbouring molecules

Question 22

pd - pd forces are stronger than…
but not….

Answer 22

id - id forces
H bonding

Question 23

id - id are the weakest type of bond. true or false?

Answer 23

true

Question 24

NOx pollution can cause….

Answer 24

acid rain

Question 25

radicals have an…

Answer 25

unpaired electron

Question 26

what makes a reaction a propagation reaction?

Answer 26

a radical is used and produced to continue the reaction

Question 27

when nitrogen monoxide reaches the atmosphere what is seen?

Answer 27

colorless gas turns brown

Question 28

a student predicts that C-Cl is more polar than C-I and therefore chloroethane will react faster than iodoethane. comment on this prediction

3 marks

Answer 28

1. C-Cl is more polar than C-I
2. however bond strength is more important and the C-Cl is stronger
3. so the ppt forms faster with iodoethane

Question 29

pd - pd forces arise due to…

Answer 29

differences in atoms electronegativity in a covalent bond

Question 30

id - id forces arise due to…

Answer 30

uneven distributions of electrons creating temporary dipoles that induce dipoles in adjacent molecules

Question 31

the main polluting effect of NO2 in the atmosphere is….

Answer 31

helps form acid rain