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Inorganic Chemistry > Group 7 - The Halogens > Flashcards

Group 7 - The Halogens Flashcards

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1
Q

What does F2 look like

A

Pale yellow gas

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2
Q

What does Cl2 appear as

A

A pale green gas

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3
Q

How does Br2 appear

A

Dark red/ brown/ orange liquid

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4
Q

How does I2 appear

A

Dark purple/ black solid

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5
Q

What is the trend in atomic radius for group 7

A

Increases down the group

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6
Q

What is the trend in electronegativity for group 7

Why?

A

Decreases down the group

Size increases
More shielding
So ability of nucleus to attract electrons is reduced

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7
Q

What is the trend in boiling point for group 7

Why

A

Boiling point increases down the group

All halogens are diatomic and as you go down the group the size of the atom increases and there are more Van der Waals forces between molecules

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8
Q

Halogens act as oxidising agents

True or false?

A

True

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9
Q

What happens when a halogen acts as an oxidising agent

A

Each halogen Atom gains an electron

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10
Q

What is the trend in the ability as an oxidising agent in group 7

Why

A

Decreases down the group

Atomic radius increases down the group and shielding increases
Halogen atom gains an electron less readily

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11
Q

Method to test displacement reaction

A

Aqueous solutions of the halogens are added drop-wise to a colourless solution containing halide ions; solutions of Potassium Chloride, Potassium bromide, and potassium iodide are usually added as the salts

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12
Q

What observations are seen when Cl2 is added to potassium bromide
Why?

Ionic equation for this reaction

A

Yellow/ brown solution of Br2
Cl2 oxides Br-

2Br- +Cl2 —>2Cl- +Br2

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13
Q

Observation for Cl2 added to potassium iodide
Why
Give ionic equation

A

Brown solution/ black PPT
Cl2 oxides I-
2I- +Cl2 —> 2Cl- +I2

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14
Q

Observations for Br2 + KCl

Why

A

No visible change

Br2 is not able to oxidise Cl2

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15
Q

Observation for Br2 + KI

A

Brown solution/ black PPT
Br2 oxidises I-
2I- + Br2 —> 2Br- + I2

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16
Q

Observation for I2 added to KCl

A

No visible change

I2 is not able to oxidise Cl-

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17
Q

What can chlorine oxidise

A

Br- and I-

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18
Q

What can Bromine oxidise

A

I- but not Cl-

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19
Q

What will iodine oxidise

A

Neither Cl- nor Br-

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20
Q

Which halogens are the strongest and weakest oxidising agents

A

F2 is the strongest

I2 is the weakest

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21
Q

Trend in ability of a halide ion to act as a reducing agent

A

Increases down group 7

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22
Q

How is trend in reducing powers of halide ions shown?

A

Reaction of solid halide salts with concentrated sulphuric acid

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23
Q

Oxidation state of S in H2SO4

A

+6

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24
Q

What can the S in H2SO4 be reduced to

A

+4, 0, or -2 depending on reducing power of the halide ion

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25
Q

What is produced from NaF + H2SO4

What redox reaction occurs

A

Na2SO4 + 2HF

No redox reaction occurs as F- is not a strong enough reduction agent to reduce S in H2SO4

Cl- is the same

26
Q

Acid-base reaction for NaBr + H2SO4

Redox reaction of NaBr to give SO2 and half equation

A

2NaBr + H2SO4—> Na2SO4 + 2HBr

2H+ + H2SO4 + 2Br- —> Br2 + SO2 + 2H2O
2e- +2H+ +H2SO4 —> SO2 + H2O

27
Q

Equation for NaI + H2SO4 acid base reaction

A

2NaI + H2SO4–> Na2SO4 +2HI

28
Q

What are the 3 different products from the 3 redox reactions for NaI + H2SO4

A

SO2 - choking gas
S - yellow solid
H2S - smell of rotten eggs

29
Q

How to identify HF, HCl, HBr, and HI (observation)

A

Misty fumes

30
Q

Observation for production of Br2

I2?

A

Brown gas

Black solid/ purple gas

31
Q

Equation for redox reaction including I- to produce SO2

A

2H+ + H2SO4 + 2I- —> SO2 + 2H2O + I2

32
Q

I- redox reaction to produce S

A

6H+ + H2SO4 + 6I- —> S +4H2O + 3I2

33
Q

I- redox reaction to produce H2S

A

H2SO4 + 8H+ +8I- —> 4I2 + H2S + 4H2O

34
Q

Strongest and weakest reducing agents of Halogens

A 
Strongest = I-
Weakest = F-
35
Q

Which silver halides are soluble and insoluble

A

Soluble: Silver fluoride
Insoluble: silver chloride, bromide, iodide

36
Q

Why is HNO3 added to an aqueous halide solution before silver nitrate test

A

To remove hydroxides and carbonates that would form a precipitate

37
Q

What colour PPT does each halide produce when added to AgNO3 and how soluble are they in NH3

A

F- : none as AgF is soluble
Cl-: white; soluble in dilute NH3
Br-: cream; partially soluble in dilute NH3, soluble in conc NH3
I-: yellow; insoluble in conc NH3

38
Q

What is formed when Cl2 is dissolved in water

A

HCl and chloric acid (HClO)

39
Q

Equation for Cl2 dissolving in water

Is Cl2 oxidised or reduced?

What is the equilibrium mixture called and what colour is it

A

Cl2+H2O (equilibrium sign) HCl + HClO

Both this is called disproportionation

Chlorine water
Pale green

40
Q

What colour does litmus paper turn in chlorine water

Why

A

Red as Both reaction products are acidic

Red then disappears and the UI turns white because HClO is a v effective bleach

41
Q

Equation for chlorine and water in bright sunlight

What is oxidised and reduced

A

2Cl2 + 2H2O—> 4HCl + O2

Chlorine oxidises water to O2
Chlorine is reduced to chloride ions

42
Q

Why does chlorine water’s green colour fade in bright sunlight

A

Cl2 is converted to HCl and O2 which are colourless

43
Q

Chlorine is toxic. Why is it still used to disinfect water

A

Health benefits outweigh the risks

44
Q

Equations for chlorine reacting with cold dilute NaOH

A

Cl2 +2NaOH—> H2O + NaCl + NaClO

Cl2 +2OH- —> H2O + Cl- +ClO- (ionic equation)

45
Q

Why is Cl2 + NaOH of great commercial importance

A

NaClO is the active ingredient in household bleach

46
Q

Test for CO3 2- ions

A

Add HCl

CO2 gas given off (effervescence)

47
Q

Test for NH4+

A

Warm carefully
Do not allow to spit
Ammonia gas given off
Which will turn damp litmus blue

48
Q

Test for Ba2+

A

Add sulphuric acid

White ppt of barium sulphate produced

49
Q

Test for OH-

A

Add magnesium chlorine
White ppt of magnesium hydroxide formed

Or

Add universal indicator
Turn blue

50
Q

What must always be included when writing equations for group two metals and water

A

State symbols

51
Q

When testing for halides what state must they be in

A

Aqueous

52
Q

If a procedure asks the product to be pure what must you include

A

Filter
Wash
Dry

53
Q

2 things to mention when discussing reducing ability

A

Size of ion

Attraction of nucleus to e-

54
Q

Colour of Br(2) as gas

A

BROWN gas

55
Q

Colour of I2(g)

A

PURPLE gas

56
Q

Normal reaction of chlorine and water

A

Cl2 + water —-> HCl + HClO

Disproportionation

57
Q

What are the products of mixing Cl2 and water

A 
HCl
Chloric acid (a weak acid)
58
Q

Chlorine in sunlit water

A

Cl2 + H2O —-> HCl + O2

Pale Green Colourless

59
Q

Products of Cl2 + water in sunlight

A

HCl

O2

60
Q

Observation when Cl2 is added to KBr

A

Yellow/ brown solution

61
Q

Observation when Cl2 is added to I-

A

Black PPT

dark brown solutions

62
Q

Observation when Br2 is added KI solution

A

Black PPT

Dark brown solution

Inorganic Chemistry (6 decks)

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