Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AQA A Level Chemistry > 2.3 Group 7, The Halogens > Flashcards

2.3 Group 7, The Halogens Flashcards

1
Q

What colour is fluorine?

A

Pale yellow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What colour is chlorine?

A

green

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What colour is bromine?

A

red-brown

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What colour is iodine?

A

grey

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What physical state is fluorine at room temperature?

A

gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What physical state is chlorine at room temperature?

A

gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What physical state is bromine at room temperature?

A

liquid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What physical state is iodine at room temperature?

A

solid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Boiling points _____ down the group

A

increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why do boiling points increase down the group? (3)

A
  • ∵ Van der Waals forces between molecules
  • Increase with size or Mr or surface area
  • More energy needed to overcome these forces

Trend is shown in changes of physical state from fluorine (gas) to iodine (solid))

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Electronegativity _______ down the group

A

decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why does electronegativity decrease down the group? (2)

A
  • Shielding increases or the atomic size increases
  • Weaker attraction by nucleus for bonding pair of electrons in the covalent bond
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Halogens become _____ oxidising down the group

A

less

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why do halogens become less oxidising down the group?

A
  • Get less reactive down the group ∵ atoms become larger
  • Outer shell further away from nucleus ∴ electrons less attracted to it
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How can you see the relative oxidising strengths of halogens?

A

By displacement reactions with halide ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the basic rule for halogens in a displacement reaction with halide ions

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What can we use these displacement reactions (halogens and halides) for?

A

To help identify which halogen (or halide) is present in solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why can’t you investigate fluorine in aqueous solution?

A

∵ it reacts with water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Name 2 uses of chlorine

A
  • Used to kill bacteria in water
  • Mix it with sodium hydroxide to make bleach
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe how you get bleach

A

If you mix chlorine gas with cold, dilute, aqueous sodium hydroxide, you get sodium chlorate(I) solution (NaClO(aq)) = bleach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Write an equation to show how bleach is made

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Write the oxidation states of chlorine in this equation

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What do the oxidation states of chlorine in this equation tell us?

A

Oxidation state of Cl goes up and down, meaning chlorine is both oxidised and reduced. This is called disproportionation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Name 3 uses of sodium chlorate(I) solution (bleach)

A
  • Water treatment (kills bacteria)
  • Bleach paper and textiles
  • Cleaning toilets
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
When you mix chlorine with water, what does it undergo?
Disproportionation
26
Write an equation to show the reaction of chlorine with water to form chloride ions and chlorate(I) ions. Include the oxidation states for chlorine.
27
In sunlight, what can chlorine do to water & what does this form?
Can decompose water to from chloride ions and oxygen
28
Write an equation to show the reaction of chlorine with water to form chloride ions and oxygen
29
\_\_\_\_\_\_ ____ kill bacteria
Chlorate(I) ions
30
Chlorine is \_\_\_
toxic
31
Name 3 advantages of adding chlorine to water supplies
Chlorine is important part of water treatment * Kills pathogens * Some chlorine persists in water and prevents reinfection further down supply * Prevents growth of algae, eliminating bad tastes and smells, & removes discolouration caused by organic compounds
32
Describe disadvantages of adding chlorine to water supplies (3)
Risks from using chlorine to treat water * Wasteful as most potable water not used for drinking- used in washing clothes * Some people suffer eye irritation * Can react with organic compounds to produce harmful substances (carcinogenic)
33
Reducing Power of Halides ______ Down the Group
Increases
34
Why does the reducing power of halides increase down the group?
(To reduce something, halide ion needs lose electron from its outer shell) * As you go down group, attraction between outer electron gets weaker ∵ * Larger atomic radius * So electrons further away from +ve nucleus * More shielding * So further down group halide ion is = easier it loses electrons & greater its reducing power
35
Describe the test for halides
1. Add dilute nitric acid (HNO3) and then silver nitrate solution (AgNO3) 2. Precipitate is formed (of silver halide)
36
Test for Halides What is the result for fluoride?
No precipitate
37
Test for Halides What is the result for chloride?
White precipitate of silver chloride
38
Test for Halides What is the result for bromide?
Cream precipitate of silver bromide
39
Test for Halides What is the result for iodide?
Yellow precipitate of silver iodide
40
Test for Halides Why do you add dilute nitric acid?
To remove ions which may interfere with test
41
Test for Halides Write the general equation
42
Fill in the gaps (speed)
43
Test for Halides What can you do to be sure of your results & why does this work?
* You can test your results by adding ammonia solution * Each silver halide has a different solubility in ammonia
44
Fill in the gaps
45
What reactions reflect the trend in the reducing ability of halide ions?
Reactions of solid sodium halides with concentrated sulfuric acid
46
All halides react with concentrated sulfuric acid to give what as a product?
hydrogen halide
47
Write the equations for the reaction of NaF or NaCl with H2SO4
48
Reaction of NaF or NaCl with H2SO4 Describe the observations
Misty (white) fumes hydrogen fluoride / hydrogen chlroide
49
Name 2 features of these reactions
* HF and HCl aren't strong enough reducing agents to reduce sulfuric acid so reaction stops there * Acid –base reactions & not redox reactions * H2SO4 plays the role of an acid * Oxidation states of halide and sulfur stay the same (-1 and +6)
50
Write the equations for the reaction of NaBr with H2SO4
1. Acid-base step 2. Redox step
51
Describe the observations in this reaction
Misty fumes of hydrogen bromide gas (HBr)
52
Write the oxidation states of S & Br for the 2nd equation
53
Describe the reducing agent in these reactions
HBr is stronger reducing agent than HCl and reacts with H2SO4 in a redox reaction
54
Describe the observations in the 2nd equation
Choking fumes of SO2 and orange fumes of Br2
55
Write the equations for the reaction of Nal with H2SO4
56
Reactions of NaI with H2SO4 Write the oxidation state of S & I
57
Reactions of NaI with H2SO4 Write the oxidation state of S & I
58
Describe the reducing agent in these equations
59
Bromine reacts with phosphorus to form phosphorus tribromide. Write an equation for this reaction.
6Br2 + P4 → 4PBr3
60
Describe the role of H2SO4 in these reactions
1. H2SO4 plays the role of acid in the first step 2. Then acts as an oxidising agent in the second redox
61
State the reduction product
Sulfur dioxide
62
State the oxidation and reduction half equations for when bromine reacts with conc. sulfuric acid
* Ox ½ equation: 2Br- → Br2 + 2e- * Re ½ equation: H2SO4 + 2H+ + 2 e- → SO2 + 2H2O
63
Reactions of NaI with H2SO4 Write an equation that gives sulfur
6HI + H2SO4 → 3I2 + S + 4H2O
64
Reactions of NaI with H2SO4 Name the products
Sulfur dioxide, sulfur and hydrogen sulfide
65
Reactions of NaI with H2SO4 Describe H2SO4 role in the reactions
H2SO4 plays the role of acid in the first step producing HI & then acts as an oxidising agent in the three redox steps
66
Reactions of NaI with H2SO4 Write the oxidation half equation and 3 reduction half equations.
Oxidation * 2I- → I2 + 2e- Reduction: * H2SO4 + 2H+ + 2e- → SO2 + 2H2O * H2SO4 + 6H+ + 6e- → S + 4H2O * H2SO4 + 8H+ + 8e- → H2S + 4H2O
67
Reactions of NaI with H2SO4 Describe the observations
* Sulfur dioxide is a choking gas * Sulfur is a yellow solid * Hydrogen sulfide has a smell of bad eggs
68
2NaBr + 2H2SO4 → Na2SO4 + Br2 + SO2 + 2H2O Explain why bromide ions reacts differently from chloride ions (2)
* Br− ions are bigger than Cl− ions * ∴ Br− ions are more easily oxidised/lose an electron
69
Write an ionic equation for the reaction between chlorine and cold dilute sodium hydroxide solution
Cl2 + 2OH- → ClO- + Cl- + H2O

AQA A Level Chemistry (36 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions