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AS Chemistry - Unit 2 > Unit 3.2.5 - Group 7 > Flashcards

Unit 3.2.5 - Group 7 Flashcards

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1
Q

Name the first four halogens?

A

Fluorine, Chlorine, Bromine, Iodine

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2
Q

State the trend in boiling point of the halogens in group 7?

A

Increase as you go down the group

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3
Q

Why does the boiling point increase as you go down the halogens in group 7?

A

Because as you go down the group the atomic radius increases which increases the surface area. This in turn increases the strength of the Van der Waal’s forces, this means you require more energy to overcome them increasing the boiling points

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4
Q

State the trend of electronegativity of the halogens in group 7?

A

Decreases as you go down the group

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5
Q

Why does the electronegativity of the halogens decreases as you go down the group?

A

There are more electron shells as you go down the group, this means the atomic radius increases and so does the shielding. This means the outer electrons are less strongly attracted to the nucleus and so the electronegativity decreases

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6
Q

Are the halogens oxidising or reducing agents and why?

A

Oxidising agents as they can accept electrons and become reduced

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7
Q

State the trend in oxidising power of the halogens in group 7?

A

It reduces as you down the group

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8
Q

Why does the oxidising power of the halogens decreases as you down the group?

A

As you do down the group there are more electron shells and so the atomic radius and shielding increases and electronegativity decreases, this means they are less able to attract the electron to gain

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9
Q

Are the halide ions oxidising or reducing agents?

A

Reducing agents as they can lose electrons can become oxidised

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10
Q

State the trend in reducing power of the halide ions?

A

Increases as you down the group

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11
Q

Why does the reducing power of the halide ions increase as you do down the group?

A

Because there are more electron shells, there is a greater atomic radius and more shielding, this means the outer electrons become less strongly attached to the nucleus and so are more easily loss

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12
Q

What is the colour and physical state of fluorine?

A

Pale yellow gas

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13
Q

What is the colour and physical state of chlorine?

A

Pale green gas

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14
Q

What is the colour and physical state of bromine?

A

Dark red liquid

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15
Q

What is the colour and physical state of iodine?

A

Grey solid

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16
Q

Describe the basic trend during a displacement reaction between halogen and halide ions?

A

A halogen will displace a halide from solutions of their ions if the halide is below it in the periodic table

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17
Q

Which ions will chlorine displace?

A

Bromide and iodide

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18
Q

Which ions will bromine displace?

A

Iodide

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19
Q

Which ions will iodine displace?

A

None

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20
Q

What is the equation for the reaction between chlorine and bromide ions?

A

Cl2 + 2Br- ———> 2Cl- + Br2

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21
Q

What is the equation for the reaction between chlorine and iodide ions?

A

Cl2 + 2I- ———> 2Cl- + I2

22
Q

What is the equation for the reaction between bromine and iodide ions?

A

Br2 + 2I- ———> 2Br- + I2

23
Q

What do sodium halides react with to give hydrogen halides?

A

Concentrated sulphuric acid

24
Q

What is the equation for the reaction between sodium halides and concentrated sulphuric acid?

A

NaX + H2SO4 ———> NaHSO4 + HX

25
Q

After the reaction between sodium halides and concentrated sulphuric acid which hydrogen halides don’t react any further and why?

A

Fluoride and chloride as they aren’t strong enough reducing agents to reduce the sulphuric acid any further

26
Q

After the reaction between sodium halides and concentrated sulphuric acid, what happens to the hydrogen bromide and hydrogen iodide?

A

As bromide and iodide are strong enough reducing agents they reduce the concentrated sulphuric acid further into water and sulphur dioxide

27
Q

What is the equation for the reaction between the hydrogen halides and concentrated sulphuric acid? (this reaction is only for hydrogen bromide/iodide)

A

2HX + H2SO4 ———> X2 + SO2 + 2H2O

28
Q

Which hydrogen halide is the strongest reducing agent?

A

Hydrogen iodide

29
Q

After hydrogen iodide has reduced the concentrated sulphuric acid to sulphur dioxide and water what reaction can happen next?

A

As iodide is the strongest reducing agent it can reduce the sulphur dioxide even further into hydrogen sulphide

30
Q

What is the equation for the reaction between hydrogen iodine and sulphur dioxide?

A

6HI + SO2 ———> H2S +3I2 + 2H2O

31
Q

What does hydrogen sulphide look like and what colour does it turn blue litmus paper?

A

White fumes, red

32
Q

What does hydrogen sulphide smell like?

A

Rotting eggs

33
Q

What test can you do to identify halide ions?

A

First add dilute nitric acid and then add silver nitrate, the colour of the silver halide precipitate can tell you which halide is present

34
Q

During the silver nitrate test for halide ions why do you add dilute nitric acid first?

A

To remove any other ions which might interfere with the precipitate that is formed

35
Q

What is the equation for the reaction between the silver in the silver nitrate and the halide ions?

A

Ag+ + X- ———> AgX

36
Q

After the doing the silver nitrate test for halides what are the colour precipitates you would get for each halide?

A

Fluoride - no visible change
Chloride - white precipitate
Bromide -cream precipitate
Iodide - yellow precipitate

37
Q

What further test can you do to help to distinguish the halide ions even further ?

A

Add dilute ammonia and then concentrated ammonia

38
Q

What would you expect to see for each halide ion if you added dilute ammonia and then concentrated ammonia after doing the silver nitrate test?

A

Fluorine - no visible change
Chlorine - precipitate dissolves in dilute ammonia
Bromine - precipitate dissolved in concentrated ammonia
Iodide - precipitate is insoluble and so you would get no visible change

39
Q

When you mix chlorine and water together what type of reaction happens?

A

Disproportionation

40
Q

What does a disproportionation reaction mean in terms of when chlorine is mixed with water?

A

It means that some chlorine is being oxidised where as some is being reduced

41
Q

What is the equation for the reaction between chlorine and water and what are the products called?

A

Cl2 + H2O ———> HCl + HClO

Hydrochloric acid and chloric acid

42
Q

What is added to water to treat it and in swimming pools to remove any bacteria?

A

Chlorine

43
Q

What are 4 advantages about adding chlorine to the water?

A
  1. ) kills microorganism that cause disease
  2. ) prevents the growth of algae
  3. ) eliminates any bad tastes and smells
  4. ) removes any discolouration
44
Q

What are 3 disadvantages about adding chlorine to water?

A
  1. ) chlorine is dangerous if breathed in as it irritates the respiratory system
  2. ) if it touches the skin or eyes it can cause serve burns
  3. ) chlorine in the water can react with organic compounds to form chlorinated hydrocarbons which can cause cancer and contribute to the destruction of the ozone layer
45
Q

Even though chlorine is toxic why is it added to water?

A

Because the benefits outweigh chlorines toxic effect

46
Q

What do you have to mix with chlorine gas to get bleach?

A

Cold, dilute aqueous NaOH

47
Q

What compound is called bleach?

A

sodium chlorate solution

48
Q

What is the equation for the reaction that forms bleach?

A

2NaOH + Cl2 ———> NaClO + NaCl + H2O

49
Q

What are the three main uses of bleach?

A
  1. ) in water treatment
  2. ) to bleach paper and textiles
  3. ) in cleaning
50
Q

When you mix chlorine with potassium bromide what colour solution would you expect to see and why?

A

Orange solution - the chlorine will displace the bromide ions

51
Q

When you mix chlorine with potassium iodide what colour solution would you expect to see and why?

A

Brown solution - the chlorine will displace the iodide ions

52
Q

When you mix bromine with potassium iodide what colour solution would you expect to see and why?

A

Brown solution - the bromine will displace the iodide ions

AS Chemistry - Unit 2 (11 decks)

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