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Chemistry Year 12 > group 7 3.2.3 > Flashcards

group 7 3.2.3 Flashcards

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1
Q

what colour does fluorine produce

A

Pale yellow gas

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2
Q

what colour is chlorine gas

A

Pale green gas

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3
Q

what’s the colour for bromine

A

a brown- orange liquid

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4
Q

what colour is iodine solid

A

grey solid

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5
Q

what’s the trend in boiling and melting point down g7

A

increases down the group
- molecules become larger so have more electrons and have larger van de waals forces
- as intermolecular forces gets larger more energy is needed to overcome the forces

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6
Q

what’s the trend in states from the top of the group to the bottom

A

gas at the top (F)
solid at the bottom (I)

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7
Q

what is electronegativity

A

the relative tendency of an atom in a molecule to attract electrons in a covalent bond to itself

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8
Q

what’s the trend in electronegativity down the group

A

Decreases
•The atomic radii increases due to increasing number of shells.
• The nucleus is less able to attract the bonding pair of electrons

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9
Q

what’s the trend in electronegativity down the group

A

Decreases
•The atomic radii increases due to increasing number of shells.
• The nucleus is less able to attract the bonding pair of electrons

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10
Q

as we go down the group are the halogens more or less oxidising

A

less oxidising

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11
Q

which halogen does chlorine displace

A

Both bromide and iodine ions

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12
Q

which halogen does bromide displace

A

iodide ions

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13
Q

which halogen will iodide displace

A

None

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14
Q

what’s the colour of chlorine solution

A

Colourless

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15
Q

what’s the colour of bromine solution

A

yellow solution

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16
Q

what’s the colour of iodine solution

A

brown solution

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17
Q

what’s the reaction and colour change when chlorine displaces potassium bromide solution

A

yellow solution is made , Cl has displaced Br
Cl2 + 2Br- => 2Cl- + Br2

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18
Q

what’s the reaction and colour change when chlorine displaces potassium iodide

A

brown solution , Cl has displaced I
Cl2(aq) + 2I- => 2Cl-(aq) + I2 (aq)

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19
Q

what’s the reaction and colour change when bromine displaces potassium iodide

A

brown solution , Br has displaced I
Br2 (aq) + 2I-(aq) => 2Br-(aq) + I2(aq)

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20
Q

what is a disproportionation reaction

A

An element simultaneously oxidises and reduces

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21
Q

what type of reaction is used to make bleach ( NaClO)

A

Disproportionation

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22
Q

what’s the reaction to make bleach

A

2NaOH(aq) + Cl2(aq) => NaClO(aq) + NaCl(aq) + H2O(l)

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23
Q

what are the uses of bleach

A
  • treating water
  • bleaching paper and fabrics
  • cleaning agents
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24
Q

why is chlorine added to water

A
  • to kill bacteria
  • used to treat drinking water and the water in swimming pools
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25
Q

why is chlorine added to water even though it’s toxic

A

the benefits to health of water treatment by chlorine outweigh its toxic effects

26
Q

what’s the reaction of chlorine and water

A

H2O (l) + Cl2(g) => 2H+(aq) + Cl-(aq) + ClO-(aq)
Produces Chlorate ions

27
Q

what’s the reaction of chlorine with water and sunlight

A

2Cl2(g)+ 2H2O(l) => 4H+(aq) +4Cl-(aq) + O2(g) + 4HCl

28
Q

what are the advantages of chlorinating drinking water

A
  • destroys microorganisms that cause disease
  • long lasting so reduces bacteria build up further down the supply
  • reduces the growth of algae that discolours water and gives it a bad taste and smell
29
Q

what are the disadvantages of chlorinating drinking water

A
  • chlorine gas is toxic and irritates the respiratory system
  • liquid chlorine causes severe chemical burns to the skin
  • chlorine can react with organic compounds present in the water to make chloroalkanes which link with causing cancer
30
Q

what are two tests with halide ions

A

1) halide reactions with sulfuric acid
2) halide reactions with silver nitrate solution

31
Q

Why are halide ions stronger reducing agents as we go down the group

A

• halide ions lose an electron in reactions
- as we go down the group the ionic radius increases
- the distance between the nucleus and outer electrons becomes larger are there is more shielding so the attractive force gets weaker .
- the outer electron is lost more readily and this is why I- is a more powerful reducing agent than F-

32
Q

what role does H2SO4 play in reacting with halide ions in acid base reactions

A

Proton donor

33
Q

why doesn’t a redox reaction occur when H2SO4 reacts with fluoride and chloride ions

A

H2SO4 is not strong enough an oxidising reagent to oxidise the chloride and the fluoride ions .
Only acid-base reactions occur

34
Q

what is the acid base reaction of H2SO4 and NaF and the observation

A

NaF(s) + H2SO4(l) => NaHSO4(s) + HF(g)
White steamy fumes of HF are evolved

35
Q

what is the acid base reaction of H2SO4 and NaCl and the observation

A

NaCl(s) + H2SO4(l) => NaHSO4(s) + HCl(g)
White steamy fumes of HCl are evolved

36
Q

why is a redox reaction taken place with Bromide ions and h2so4

A

Br- ions are stronger reducing agents than Cl- and F- and after the initial acid - base reaction reduce the sulfur in H2SO4 from +6 to +4 in SO2

37
Q

what is the acid base reaction of H2SO4 and NaBr and the observation

A

NaBr(s) + H2SO4 (l) => NaHSO4 (s) + HBr(g)

38
Q

what is the oxidation half equation for bromine

A

2Br- => Br2 + 2e-

39
Q

what is the oxidation half reaction for H2SO4

A

H2SO4 + 2H+ +2e- => SO2 + 2H2O

40
Q

what’s the redox reaction of HBr (product from acid base reaction )reacting with H2SO4

A

2HBr + H2SO4 => Br2(g) + SO2(g) + 2H2O(l)

41
Q

what are the observations of Bromide ions reacting with H2sO4

A

White steamy fumes of HBr are evolved
Orange fumes of bromine are also evolved and a colourless acidic gas of SO2

42
Q

why do redox reactions occur in the reaction of iodide ions and h2so4

A

Iodide ions are the strongest halide reducing agents .
They can reduce sulfur from +6 to +4 in So2 to 0 in S to -2 In H2S

43
Q

what are the reactions between NaI and H2SO4

A

Acid base reaction :
1) NaI(s) + H2SO4(l) => NaHSO4(s) + HI(g)
Redox reaction :
2) 2HI + H2SO4 => I2(s) + SO2(g) + 2H2O(l)
3) 6HI + H2SO4 => 3I2 + S(s) + 4H2O(l)
4) 8HI + H2SO4 => 4I2(s) + H2S(g) + 4H2O (l)

44
Q

what is the oxidation half equation for Iodide

A

2I- => I2 + 2e-

45
Q

what are the reduction half equations for H2SO4 for I-

A

1) H2SO4 + 2H+ + 2e- => SO4 + 2H2O
2) H2SO4 + 6H+ + 6e- => S + 4H2O
3) H2SO4 + 8H+ + 8e- => H2S + 4H2O

46
Q

what is the role of H2SO4 in the acid base reactions with iodide

A

Role of an acid (proton donor)

47
Q

what’s the role of h2So4 when in the three redox reactions with Iodide

A

Oxidising agent

48
Q

what are the observations of h2So4 reacting with iodide ions

A
  • white steamy fumes of HI evolved
  • Black solid and purple fumes of iodine are also evolved
  • A colourless acidic gas of SO2
  • a yellow solid of sulfur
  • H2S , a gas with a bad egg smell
49
Q

how do you test for halide ions

A

Add dilute nitric acid (HNO3) then silver nitrate solution ( AgNO3) .
The colour of the precipitate will help you identify the halide ion

50
Q

what’s the reaction and observation of chloride ions with AgNO3

A

Chlorides produce a white ppt
Ag+ (aq) + Cl-(aq) => AgCl(s)

51
Q

what’s the reaction and observation of bromide ions with AgNO3

A

Cream ppt
Ag+(aq) + Br-(aq) => AgBr(s)

52
Q

what’s the reaction and observation of iodide ions with AgNO3

A

Pale yellow ppt
Ag+(aq) + I-(aq) => AgI(s)

53
Q

why is ammonia solution used after reacting halide ions with AgNO3 to help identity the halide ion

A

The silver halide ppt can be treated with ammonia solution to help differentiate between them if the colours look similar

54
Q

what’s the observation with AgCl (s) and aqueous ammonia

A

Dissolves

55
Q

what’s the observation with AgCl (s) and concentrated ammonia

A

Dissolves

56
Q

what’s the observation with AgBr (s) and aqueous ammonia

A

Does not dissolve

57
Q

what’s the observation with AgBr (s) and concentrated ammonia

A

dissolves

58
Q

what’s the observation with AgI (s) and aqueous ammonia

A

does not dissolve

59
Q

what’s the observation with AgI (s) and concentrated ammonia

A

does not dissolve

60
Q

in what order does the solubility of the silver halides in ammonia decrease

A

AgF> AgCl> AgBr> AgI

61
Q

what is the reaction of silver chloride (AgCl) and DILUTE ammonia to produce a complex ion

A

AgCl(s) +2NH3(aq) => [Ag(NH3)2]+(aq) +Cl- (aq)

62
Q

what’s the reaction between silver bromide (agbr) with concentrated ammonia to form a complex ion

A

AgBr(s) + 2NH3(aq) => [Ag(NH3)2]+(aq) + Br-(aq)

Chemistry Year 12 (24 decks)

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