GROUP 7 - HALOGENS

Question 1

What are the physical properties of fluorine? (1)

Answer 1

pale yellow gas.

Question 2

What are the physical properties of chlorine? (1)

Answer 2

greenish gas.

Question 3

What are the physical properties of bromine? (1)

Answer 3

a red-brown liquid

Question 4

What are the physical properties of iodine? (1)

Answer 4

a black solid.

Question 5

what physical characteristic do all of the halogens share? (1)

Answer 5

they all have a characteristic called the swimming bath smell

Question 6

what are some of the odd characteristics of fluorine? (2)

Answer 6

-the F-F bond is unexpectedly weak compared to the trend of the halogens, the small size of the fluorine atom leads to repulsion between the non-bonding electrons because they are so close together.

Question 7

why do the size of the atoms get bigger going down the group? (1)

Answer 7

each element has one extra filled main level of electrons compared to the one above.

Question 8

why do electronegativities decrease going down the group? (2)

Answer 8

electronegativities depend on the attraction between the nucleus and bonding electrons in the outer shell, this in turn depends on a balance between the number of protons in the nucleus and the distance between the nucleus and the bonding electrons plus shielding.

Question 9

why do melting and boiling points increase going down the group? (1)

Answer 9

larger atoms have more electrons and this makes the van der waals forces between molecules stronger - the lower the boiling point, the more volatile the element.

Question 10

why does the oxidising ability increase down the group? (1)

Answer 10

halogens usually react by gaining electrons to become negative ions (they are oxidising reagents).

Question 11

how do halogens react with metal halides in solution? (1)

Answer 11

halogens will react metal halides in solution so that the halide compound will be displaced by a more reactive halogen but not a less reactive one. (displacement) - the metal ions are spectator ions.

Question 12

what do halide ions act as in reactions? (1)

Answer 12

act as reducing agents, in these reactions the halide ions lose electrons and become halogen molecules

Question 13

what is the trend in reducing ability in the halogens? (2)

Answer 13

the larger the ion, the more easily it loses an electron this is because the electron is lost from the outer shell which is further from the nucleus as the ion gets larger so the attraction to the outer electrons is less (increase in reducing power going down the group)

Question 14

what reaction can be used to produce hydrogen chloride gas? (1)

Answer 14

solid sodium halides react with sulfuric acid

Question 15

what are the properties of chlorine? (2)

Answer 15

chlorine is a poisonous gas, but it is soluble and forms a major part of water treatment.

Question 16

how does chlorine help in water treatment?

Answer 16

it is used to purify swimming pools, it is used to prevent life threatening diseases.

Question 17

DISPLACEMENT

What happens when chlorine ions and bromine molecules? (1)

Answer 17

stays a yellow solution (no reaction)

Question 18

DISPLACEMENT

What happens when chlorine ions and iodine molecules? (1)

Answer 18

stays a brown solution (no reaction)

Question 19

DISPLACEMENT

What happens when bromine ions and chloride molecules? (1)

Answer 19

yellow solution forms (bromine displaces chlorine.)

Question 20

DISPLACEMENT

What happens when bromine ions and iodide molecules? (1)

Answer 20

stays a brown solution (no reaction)

Question 21

DISPLACEMENT

What happens when iodine ions and bromine molecules? (1)

Answer 21

brown solution forms (iodine displaces bromide)

Question 22

DISPLACEMENT

What happens when iodine ions and chloride molecules? (1)

Answer 22

brown solution forms (iodine displaces chlorine)

Question 23

AQEOUS SOLUTION+ORGANIC SOLVENTS

What happens when Chlorine ions and bromide molecules react? (1)

Answer 23

yellow solution (organic layer)

Question 24

AQUEOUS SOLUTION+ORGANIC SOLVENTS

What happens when Chlorine ions and iodide molecules react? (1)

Answer 24

purple solution (organic layer)

Question 25

AQUEOUS SOLUTION+ORGANIC SOLVENTS

What happens when bromine ions and chloride molecules react? (1)

Answer 25

yellow solution (organic layer)

Question 26

AQUEOUS SOLUTION+ORGANIC SOLVENTS

What happens when bromine ions and Iodide molecules react? (1)

Answer 26

purple solution (organic layer)

Question 27

AQUEOUS SOLUTION+ORGANIC SOLVENTS

What happens when Iodine ions and bromide molecules react? (1)

Answer 27

yellow solution (organic layer)

Question 28

AQUEOUS SOLUTION+ORGANIC SOLVENTS

What happens when iodine ions and chloride molecules react? (1)

Answer 28

purple solution (organic layer)

Question 29

what happens when a halide ions reduces another substance? (1)

Answer 29

when a halide ions reduces another substance, the halide is oxidised to a halogen.

Question 30

what experiment is used to check the reducing power of the halogens? (1)

Answer 30

halides reacting with sulphuric acid

Question 31

what are the conclusions of the experiment with sulphuric acid? (3)

Answer 31

-chlorine does not reduce sulphuric acid
-bromine reduces sulphuric acid from S(+6) to S(+4)
-iodine reduces sulphuric acid from S(+6) to S(-2)

Question 32

what test is used to identify metal halides? (1)

Answer 32

reacting with nitric acid.

Question 33

what colour does silver fluoride present as? (1)

Answer 33

no precipitate

Question 34

what colour does silver chloride present as? (1)

Answer 34

white precipitate

Question 35

what colour does silver bromide present as? (1)

Answer 35

cream precipitate

Question 36

what colour does silver iodide present as? (1)

Answer 36

pale yellow precipitate

Question 37

what further test is conducted to establish a difference in silver halides? (1)

Answer 37

adding a few drops of concentrated of ammonia solution.

Question 38

how does silver chloride present when concentrated ammonia solution is added? (1)

Answer 38

dissolves in dilute ammonia

Question 39

how does silver bromide present when concentrated ammonia solution is added? (1)

Answer 39

dissolves in concentrated ammonia

Question 40

how does silver iodide present when concentrated ammonia solution is added? (1)

Answer 40

insoluble in concentrated ammonia

Question 41

why does silver fluoride not form a precipitate with silver nitrate? (1)

Answer 41

because it is soluble in water.

Question 42

why is dilute nitric acid added to the halide solution before adding silver nitrate? (2)

Answer 42

to get rid of any soluble carbonate or hydroxide impurities, these would interfere with the test by producing insoluble silver carbonate or insoluble silver hydroxide.

Question 43

what precipitate does silver hydroxide form in terms of failed tests for silver nitrate? (1)

Answer 43

silver hydroxide is converted into silver oxide which is a brown precipitate.

Question 44

what are the products of the reaction between sodium chloride and sulfuric acid? (2)

Answer 44

steamy fumes of hydrogen chloride and a solid product, sodium hydrogen sulphate.

Question 45

what are the products of the reaction between sodium bromide and sulfuric acid? (3)

Answer 45

steamy fumes of hydrogen bromide, brown fumes of bromine and colourless sulphur dioxide

Question 46

what are the products of the reaction between sodium iodide and sulfuric acid? (5)

Answer 46

steamy fumes of hydrogen iodide, black solid of iodine, bad egg smell of hydrogen sulphide may also see a yellow solid of sulphur and colourless sulphur dioxide.