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A-Level Chemistry > Group 7 > Flashcards

Group 7 Flashcards

1
Q

What are the characteristics of fluorine?

A

Colour- pale yellow
Physical state- gas
highly reactive

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2
Q

What are the characteristics of chlorine?

A

Colour- green
Physical state - gas
poisonous in high concentrations

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3
Q

What are the characteristics of bromine?

A

Colour- red-brown
Physical state- liquid
produces dense brown/orange poisonous fumes

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4
Q

What are the characteristics of iodine?

A

Colour- grey
Physical state-solid
produces purple gas

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5
Q

What is the trend of boiling points down the group?

A

The boiling points increase

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6
Q

Why do the boiling points increase down the group?

A

Down the group, the molecules are larger
There are more electrons
Therefore, there are stronger van der Waals forces
More energy is required to break the forces

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7
Q

What is the trend of electronegativity up the group?

A

The electronegativity increases

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8
Q

Why does the electronegativity increase up the group?

A

The atomic radius decreases
there is less shielding
there is a stronger force of attraction on the electrons

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9
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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10
Q

Why is fluorine the most electronegative element?

A

It is the smallest atom with the most need to fill its shell

it has the least number of electrons and shells

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11
Q

What happens when a halogen reacts with a halide in a solution?

A

A halogen will displace a halide from the solution if the halide is below the halogen in the periodic table

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12
Q

What is the trend of oxidising strength down the group?

A

The oxidising strength decreases down the group

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13
Q

What happens when potassium chloride reacts with chlorine?

A

No reaction

Remains green

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14
Q

What happens when potassium chloride reacts with bromine?

A

No reaction

Remains orange

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15
Q

What happens when potassium chloride reacts with iodine?

A

No reaction

Remains brown

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16
Q

What happens when potassium bromide reacts with chlorine?

A

Orange solution formed

Chlorine has been displaced by bromine

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17
Q

What happens when potassium bromide reacts with bromine?

A

No reaction

Remains orange

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18
Q

What happens when potassium bromide reacts with iodine?

A

No reaction

Remains brown

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19
Q

What happens when potassium iodide reacts with chlorine?

A

Brown solution formed

Chlorine displaced by iodine

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20
Q

What happens when potassium iodide reacts with bromine?

A

Brown solution formed

Bromine displaced by iodine

21
Q

What happens when potassium iodide reacts with iodine?

A

No reaction

22
Q

What is the trend of the reducing power of the halides down the group?

A

The reducing power increases down the group

23
Q

Why does the reducing power increase down the group?

A
  • the ions get bigger down the group
  • the further away the outer electrons are from the nucleus
  • there is more shielding
  • weaker force of attraction
24
Q

What happens when the reducing power increases down the group?

A

The greater the reducing power
the greater the reactivity
the faster the reduction reactions take place

25
Q

What happens when fluoride reacts with concentrated sulfuric acid?

A

NaF(s) + H2SO4(aq) → NaHSO4(s) + HF(g)

26
Q

What happens when chloride reacts with concentrated sulfuric acid?

A

NaCl(s) + H2SO4(aq) → NaHSO4(s) + HCl(g)

27
Q

Why are the reactions between fluoride and chloride with concentrated sulfuric acid not redox reactions?

A

HF and HCl aren’t strong enough reducing agents to reduce the sulfuric acid
The oxidation states of the halide and sulfur remain the same

28
Q

What happens when bromide reacts with concentrated sulfuric acid?

A

NaBr(s) + H2SO4(aq) → NaHSO4(s) + HBr(g)

2HBr(aq) + H2SO4(aq) → Br2(g) + SO2(g) + 2H2O(l)

29
Q

What happens when iodide reacts with concentrated sulfuric acid?

A

NaI(s) + H2SO4(aq) → NaHSO4(s) + HI(g)
2HI(g) + H2SO4(aq) → I2(s) + SO2(g) + 2H2O(l)
6HI(g) + SO2(aq) → 3I2(s) + H2S(g) + 2H2O(l)

30
Q

What observations can be made when bromide reacts with concentrated sulfuric acid?

A

steamy fumes of HBr are produced
Red fumes of Br2
colourless, acidic gas, SO2

31
Q

What observations can be made when iodide reacts with concentrated sulfuric acid?

A 
steamy fumes of HI are produced
black solid and purple fumes of I2
colourless acidic gas, SO2
yellow solid, sulfur
toxic, rotten egg smell, H2S
32
Q

What observations can be made when iodide reacts with concentrated sulfuric acid?

A 
steamy fumes of HI are produced
black solid and purple fumes of I2
colourless acidic gas, SO2
yellow solid, sulfur
toxic, rotten egg smell, H2S
33
Q

How would you test for halides using silver nitrate

A

Add nitric acid to the solution to remove ions which may give a false positive result
Add a few drops of silver nitrate solution
A precipitate is formed
The colour of the precipitate will determine the halide present

34
Q

What is the colour of the precipitate when silver nitrate is used to test chlorides?

A

White precipitate

35
Q

What is the colour of the precipitate when silver nitrate is used to test bromides?

A

Cream precipitate

36
Q

What is the colour of the precipitate when silver nitrate is used to test iodides?

A

Yellow precipitate

37
Q

What is the trend of solubility of silver halides in ammonia?

A

The solubility decreases down the group

38
Q

What observations would be made when ammonia is added to silver chloride?

A

White precipitate

Silver chloride dissolves in dilute ammonia

39
Q

What observations would be made when ammonia is added to silver bromide?

A

Cream precipitate

Silver bromide dissolves in concentrated ammonia

40
Q

What observations would be made when ammonia is added to silver iodide?

A

Yellow precipitate

Insoluble in both dilute and concentrated ammonia

41
Q

Why is chlorine used in water?

A

It kills bacteria

42
Q

What happens when chlorine reacts with water?

A

It undergoes disproportionation

43
Q

What is disproportionation?

A

A reaction where an is element simultaneously oxidised and reduced

44
Q

What happens when chlorine reacts with water?

A

Cl2(g) + H2O(l) → 2H+(aq) + Cl-(aq) + ClO(aq)

45
Q

What happens when chlorine reacts with water in sunlight?

A

2Cl2(g) + 2H2O(l) → 4H+(aq) + 4Cl-(aq) + O2(g)

46
Q

What are the disadvantages of using chlorine for water treatment?

A
  • chlorine gas is harmful
  • liquid chlorine causes severe burns
  • chlorine reacts with organic compounds in water forming chlorinated hydrocarbons which are carcinogenic
47
Q

Why is chlorine still used in water treatment?

A

The benefits to health of water treatment by chlorine outweighs its toxic effects

48
Q

What happens chlorine reacts with cold, dilute aqueous NaOH?

A

2NaOH(aq) + Cl2(g) → NaClO(aq) + NaCl(aq) + H2O(l)

49
Q

What is sodium chlorate(NaClO) used for?

A

bleach

A-Level Chemistry (30 decks)

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