Group 7 Flashcards

1
Q

State and explain the trend in group 7 melting/boiling points

A

Increases because:- Halogens exist as non-polar diatomic molecules- Weak van der waals forces exist between the molecules (IMF’s) which are broken when boiled/melted- Induced dipole forces become stronger down the group as Mr increases this is because more electrons involved in the induced dipoles

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2
Q

State and explain the trend in group 7 electronegativity

A

Decreases because:- Shielding increases - Effective nuclear charge decreases - Decreases its ability to attract a bonding pair of electronse.g. fluorine can form a stronger dipole than iodine

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3
Q

What state is fluorine in at room temp?

A

Gas

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4
Q

What state is chlorine in at room temp?

A

Gas

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5
Q

What state is bromine in at room temp?

A

Liquid

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6
Q

What state is iodine in at room temp?

A

Solid

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7
Q

What are halogens?

A

Oxidising agents

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8
Q

What are halides?

A

Reducing agents

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9
Q

Which halogen is the strongest oxidising agent and why?

A

Fluorine because it has the highest effective nuclear charge due to lowest shielding

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10
Q

Which halogen is the weakest oxidising agent and why?

A

Iodine because it has the lowest effective nuclear charge due to highest shielding

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11
Q

Which halide is the strongest reducing agent and why?

A

Iodide because it has the lowest effective charge due to having the highest shielding

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12
Q

Which halide is the weakest reducing agent and why?

A

fluoride because it has the highest effective charge due to having the lowest shielding

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13
Q

What type of reaction occurs between a halogen (aq) and a halide (aq)?

A

A displacement reaction

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14
Q

What is observed when Cl2 reacts with Br-?

A

Orange solution

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15
Q

What is observed when Cl2 reacts with I-?

A

Brown Solution

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16
Q

What is observed when Br2 reacts with I-?

A

Brown Solution

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17
Q

What is the first step in testing for halide ions?

A

Add acidified silver nitrate (H+/AgNO3 (aq))

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18
Q

Why do we add acidified silver nitrate when testing for halide ions?

A

The HNO3 neutralises and carbonate or hydroxide impurities present which interfere with the halide test.

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19
Q

What does Ag2CO3 form?

A

White precipitate

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20
Q

What does AgOH form?

A

Brown precipitate

21
Q

What is the second step in testing for halides?

A

Add aqueous ammonia (NH3)

22
Q

What is the result of adding AgNO3 dropwise to a solution containing F-?

A

No precipitate AgF(aq)

23
Q

What is the result of adding AgNO3 dropwise to a solution containing Cl-?

A

White precipitate AgCl(s)

24
Q

What is the result of adding AgNO3 dropwise to a solution containing Br-?

A

Cream precipitate AgBr(s)

25
Q

What is the result of adding AgNO3 dropwise to a solution containing I-?

A

Pale yellow precipitate AgI(s)

26
Q

What is the result of adding NH3 to AgF(aq)?

A

No reaction

27
Q

What is the result of adding NH3 to AgCl(s)?

A

AgCl(s) dissolves in dilute NH3(aq)

28
Q

What is the result of adding NH3 to AgBr(s)?

A

AgBr(s) dissolves in conc NH3(aq)

29
Q

What is the result of adding NH3 to AgI(s)?

A

AgI(s) will not dissolve

30
Q

What happens if H2O is added to Cl2?

A

HCL and HCLO (chloric acid) is formed in a disproportionation reaction where Cl is both oxidised and reduced

31
Q

What is HClO used for?

A

HClO is antibacterial (oxidising agent) hence the use of chlorine in swimming pools

32
Q

What happens if 2H2O is added to 2Cl2 in the presence of UV?

A

4HCL and O2 are formed, hence why outdoor pools need chlorinating more often

33
Q

What happens if cold dilute 2NaOH is added to Cl2

A

NaCl, NaClO and H2O are formed

34
Q

What is NaClO?

A

Sodium chlorate which is an active ingredient in bleach

35
Q

What is produced when NaF and H2SO4 react together?

A

Nothing as they will not react

36
Q

What is produced when NaCl and H2SO4 react together?

A

HCl and NaHSO4

37
Q

What observations are made in the reaction between NaCl and H2SO4?

A

Steamy fumes of HCl will be given off

38
Q

What is produced when NaBr and H2SO4 react together?

A

HBr and NaHSO4

39
Q

What observations are made in the reaction between NaBr and H2SO4?

A

Steamy fumes of HBr given off

40
Q

What is the redox reaction that occurs when 2Br- ions react with H2SO4?

A

2H+ + 2Br- + H2SO4 -> BR2 + SO2 + 2H2O

41
Q

What are the observations made during the redox reaction that occurs when 2Br- ions react with H2SO4?

A

Brown fumes of Br2 and colourless fumes of SO2

42
Q

What is produced when NaI and H2SO4 react together?

A

HI and NaHSO4

43
Q

What observations are made in the reaction between NaI and H2SO4?

A

Steamy fumes of HI given off

44
Q

What is the redox reaction that occurs when 2I- ions react with H2SO4?

A

2H+ + 2I- + H2SO4 -> I2 + SO2 + 2H2O

45
Q

What are the observations made during the redox reaction that occurs when 2I- ions react with H2SO4?

A

Purple fumes of I2 and colourless gas of SO2

46
Q

What is the redox reaction that occurs when 6I- ions react with H2SO4?

A

6H+ + 6I- + H2SO4 -> 3I2 + S + 4H2O

47
Q

What are the observations made during the redox reaction that occurs when 6I- ions react with H2SO4?

A

Purple fumes of I2 and yellow solid of S

48
Q

What is the redox reaction that occurs when 8I- ions react with H2SO4?

A

8H+ + 8I- + H2SO4 -> 4I2 + H2S + 4H2O

49
Q

What are the observations made during the redox reaction that occurs when 8I- ions react with H2SO4?

A

Purple fumes of I2 and pungent gas of H2S