12 - group 17

Question 1

what are halogens

Answer 1

what group 17 elements are called, 7 electrons in outer shell

Question 2

flourine electronic configuration

Answer 2

1s²
2s², 2p5

Question 3

cholrine electronic configuration

Answer 3

1s²
2s², 2p6
3s², 3p5

Question 4

bromine electronic configuration

Answer 4

1s²
2s², 2p6
3s², 3p6, 3d10
4s², 4p5

Question 5

iodine electronic configuration

Answer 5

1s²
2s², 2p6
3s², 3p6, 3d10
4s², 4p6, 4d10
5s², 5p5

Question 6

group 17 elements properties?

Answer 6

. all non metals
. diatomic molecules at room temperature
. single covalent bond betwee. two atoms in each molecule

Question 7

F, Cl, Br, I (–>)

Answer 7

. atomic radius increases
. melting and boiling point increase
. volatility decreases
. reactivity decreases
. electronegativity decreases
. strength as oxidising agent decreases
. bond energy decreases
. thermal stability decreases
. increasing effectiveness as reducing agents
. ease to oxidise hydrogen halides increases

Question 8

what is volatility

Answer 8

the ease with which a substance evaporates

g17 have low values (simple molecular structures, weak id-id)

Question 9

F colour

Answer 9

pale yellow gas

Question 10

Cl colour

Answer 10

green/yellow gas

Question 11

bromine colour

Answer 11

orange/brown liquid

Question 12

iodine colour

Answer 12

. grey/black liquid
. purple gas

Question 13

reactions of halogens

Answer 13

. halogens + metals (h is oxidising agent) IONIC BOND
. halogens + non metals (h is oxidising agent) COVALENT BOND

Question 14

vigorous

Answer 14

a reaction that has a rapid rate of reaction

Question 15

more reactive halogens displace less reactive ones in a reaction

Question 16

immiscible

Answer 16

two liquids that do not dissolve in each other and so form two seperate layers, such as oil and water

Question 17

which colourless liquid do the halogens dissolve well in

Answer 17

cyclohexane

Question 18

flourine + hydrogen

Answer 18

H2 + F2 = 2HF
. explosive even in cool, dark conditions

Question 19

cholrine + hydrogen

Answer 19

H2 + Cl2 = 2HCl
. explosive in sunlight

Question 20

bromine + hydrogen

Answer 20

H2 + Br2 = 2HBr
. reacts slowly on heating

Question 21

hydrogen + iodine

Answer 21

H2 + I2 =REVERSIBLE= 2HI
. forms equilibrium mixture on mixing

Question 22

thermal stability

Answer 22

the resistance of a compound to breakdown by heating

Question 23

test for halide ions:

Answer 23

1) add dilute nitric acid and aqueous silver nitrate
. AgCl, white
. AgBr, cream
. AgI, pale yellow

AgNO3 + X¯ - - - - > AgX + NO3¯

2) add dilute and concentrated ammonia solution
. AgCl - dissolves, dissolves
. AgBr - insoluble, dissolves
. AgI - insoluble, insoluble

Question 24

halide ions and concentrated sulfuric acid

Answer 24

ALL PRODUCE TOXIC GASES

CHLORINE
NaCl + H2SO4 - - - > NaHSO4 + HCl
white fumes

BROMINE
NaBr + H2SO4 - - - > NaHSO4 + HBr
2HBr + H2SO4 - - - > Br2 + SO2 + 2H2O
red brown gas

IODINE
NaI + H2SO4 - - - > NaHSO4 + HI
2HI + H2SO4 - - - > I2 + SO2 + 2H2O
6HI + H2SO4 - - - > 3I2 + S + 2H2O
8HI + H2SO4 - - - > 4I2 + H2S + 4H2O
. sulfur yellow solid
. hydrogen sulfate with bad egg smell
. iodine as purple vapour

Question 25

disproportionation reaction

Answer 25

self-reduction / oxidation reaction undergone by cholrine

Question 26

chlorine in cold alkali - 15°C (disproportionation reaction)

Answer 26

Cl2 + 2NaOH - - - > NaCl + NaClO SODIUM CHLORATE + H2O . reduction 0.5Cl2 + e¯ = Cl¯ . oxidation 0.5Cl2 + 2OH¯= ClO¯ + H2O + e¯

Question 27

chlorine in hot alkali - 70°C (disproportionation reaction)

Answer 27

3Cl2 + 6NaOH - - - > 5NaCl + NaClO3 SODIUM CHLORATE + 3H2O . reduction Cl2 to NaCl 0 to - 1 . oxidation Cl2 to NaClO 0 to +5

Question 28

adding chlorine in water makes water safer to drink

Question 29

chlorine disproportionation reaction in water

Answer 29

Cl2 + H2O - - - > HCl + HClO 0,, - 1, +1

Question 30

HClO

Answer 30

chloric I acid sterilies water by killing bacteria some dissolves in water to produce ClO- (this acts as a sterilising agent)