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AQA A level Chemistry > Group 7 > Flashcards

Group 7 Flashcards

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1
Q

What does electronegativity mean

A

Relative tendency of an atom in a molecule to attract a group of elections in a covalent bond

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2
Q

What is the trend in electronegativy in group 7

A

It decreases because

  • as you go down the group the halogens get bigger
  • so the atomic radius increases which means the outer electrons are further away from the nucleus
  • so there is less attraction
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3
Q

What is the trend in melting and boiling points in group 7

A

It increases because

  • as the molecules get bigger
  • more van der waals
  • so you need more energy to break the forces
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4
Q

What colour is chlorine in water

A

Pale green

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5
Q

What colour is bromine in water

A

Yellow to orange to red

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6
Q

What is the reaction of chlorine with water

A

Cl2 + H20 -> HCL +HCLO

Or chloric acid can be written as HOCL

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7
Q

What is the use of chloric acid

A

It is an disinfectant

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8
Q

What is a disproportionation reaction

A

It is when an element is both reduced and oxidised

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9
Q

Why do we use chlorine to sterilise water even though it’s toxic

A

The benefit outweighs the costs

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10
Q

What is the reaction to make bleach

A

Cl2 + 2NAOH -> NaCL + NACLO + H20

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11
Q

What is the reaction of chlorine and water in the presence of sunlight

A

2CL2 + 2H20 -> 4HCL + O2

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12
Q

What is the trend of oxidation in group 7

A

It decreases

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13
Q

What would happen if chlorine reacts with potassium bromide

1 say what you would observe
And the ionic equation

A

Yellow solution would be formed

Cl2 + 2BR- -> 2CL- + Br2

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14
Q

What would happen if chlorine reacts with potassium iodide

1 say what you would observe
And the ionic equation

A

Brown solution

CL2 + 2I- -> 2CL-+ I2

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15
Q

What would happen if bromine reacts with potassium iodide

1 say what you would observe
And the ionic equation

A

Br2 + 2I- -> 2BR- + I2

Brown solution

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16
Q

What is the trend of reducing power in group 7

And why?

A

It increases

Why?

The ions get bigger as you go down the group. Therefore there is less of an attraction to the positive nucleus
So it’s easier to lose electrons

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17
Q

What is the reaction with chloride and concentrated sulphuric acid

Also name the Type of reaction that occurs

A

NaCL + H2S04 -> NaHSO4 + HCL

Observation

White steamy fumes from HCL- acid base reaction

(Same reaction for fluorine)

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18
Q

What is the reaction with bromide and concentrated sulphuric acid

Include observation and type of reactions

A

NaBr + H2S04 -> NaHSO4 + HBR

Observation: steamy white fumes
Type of reaction: Acid base

2HBR + H2SO4 -> Br2 + SO2 + 2H20
Observation: orange fumes of bromine and colourless acidic gas
Type of reaction: redox

19
Q

What is the reaction with iodide and concentrated sulphuric acid

Include observation and type of reactions

A

NaI + H2S04 -> NaHSO4 + HI

Observation: steamy white fumes
Type of reaction: Acid base

2HI + H2SO4 -> I2 + SO2 + 2H20
Observation: black solid and purple fumes of iodine and colourless acidic gas
Type of reaction: redox

6HI + H2SO4 -> 3 I2 + S + 4H20
Observation: yellow solid of sulphur
Type of equation: redox

8HI + H2SO4 -> 4I2 + H2S + 4H20
Observation: gas with bad egg smell
Type of equation: redox

20
Q

How would you test for halide ions

A

You add nitric acid to élimante carbonate ions

And then add Silver nitrate

21
Q

What happens when you add silver nitrate to a chloride ions

A

Ag+ + Cl- -> AgCl

White precipitate

22
Q

What happens when you add silver nitrate to a bromide ions

A

Ag+ + Br- -> AgBr

Cream precipitate

23
Q

What happens when you add silver nitrate to a iodide ions

A

Ag+ + I- -> AgI

Yellow precipitate

24
Q

If we can’t differentiate between different ions what chemical would you use

A

Ammonia

25
Q

What would happen if you add dilute ammonia to chloride ions

A

Precipitate would dissolve

26
Q

What would happen if you add dilute ammonia to bromide ions

A

No visible change

27
Q

What would happen if you add dilute ammonia to iodide ions

A

No visible change

28
Q

What would happen if you add conc ammonia to chlorine ions

A

Precipitate would dissolve

29
Q

What would happen if you add conc ammonia to bromine ions

A

Precipitate would dissolve

30
Q

What would happen if you add conc ammonia to iodide ions

A

No visible change

31
Q

What is the reaction of chlorine of water in uv light

A

Cl2 + 2H20 -> 4HCL + O2

32
Q

How would you test for halide ions

A

You add nitric acid to élimante carbonate ions

And then add Silver nitrate

33
Q

What happens when you add silver nitrate to a chloride ions

A

Ag+ + Cl- -> AgCl

White precipitate

34
Q

What happens when you add silver nitrate to a bromide ions

A

Ag+ + Br- -> AgBr

Cream precipitate

35
Q

What happens when you add silver nitrate to a iodide ions

A

Ag+ + I- -> AgI

Yellow precipitate

36
Q

If we can’t differentiate between different ions what chemical would you use

A

Ammonia

37
Q

What would happen if you add dilute ammonia to chloride ions

A

Precipitate would dissolve

38
Q

What would happen if you add dilute ammonia to bromide ions

A

No visible change

39
Q

What would happen if you add dilute ammonia to iodide ions

A

No visible change

40
Q

What would happen if you add conc ammonia to chloride ions

A

Precipitate would dissolve

41
Q

What would happen if you add conc ammonia to bromine ions

A

Precipitate would dissolve

42
Q

What would happen if you add conc ammonia to iodide ions

A

No visible change

43
Q

What is the reaction of chlorine of water in uv light

A

Cl2 + 2H20 -> 4HCL + O2

44
Q

What would happen if you added silver nitrate to fluoride ions

A

Nothing or no visible change

AQA A level Chemistry (26 decks)

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