10 - Group 7 Halogens Flashcards

1
Q

Describe and explain the trend of Group 7 electronegativity.

A
  • Decreases down Group 7
  • Down group, number of electro shells increases
  • Atomic radii increases
  • Ability of nucleus to attract bonding pair decreases
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2
Q

Describe and explain the trend in boiling points of Group 2.

A
  • Increases down group
  • Number of electrons increases
  • Number of van der Waals increases
  • Energy required to seperate molecules increases
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3
Q

Describe the trend in oxidising ability of Group 7.

A

Decreases down group

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4
Q

Define, in terms of electrons, an oxidising agent.

A

Electron acceptor

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5
Q

What colour is a bromine solution?

A

Brown maybe

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6
Q

Give the colours of an iodine solution, iodine solid, and iodine gas.

A

Brown solution
Black solid
Purple gas

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7
Q

What colour is a chlorine solution?

A

Very pale green, or colourless

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8
Q

Describe the test for a halide ion?

A
  1. Add nitric acid
  2. Add silver nitrate
  3. Add ammonia
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9
Q

Why is nitric acid added to a halide test?

A

Reacts with carbonates which would otherwise form Ag2CO3

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10
Q

Describe the precipitates formed in a silver halide test.

A
  • Fluoride forms no preciptate
  • Chloride forms a white precipitate
  • Bromine forms a cream precipitate
  • Iodide forms a yellow precipitate
    |
  • Silver chloride dissolves in dilute ammonia
  • Silver bromide dissolves in concentrated ammonia
  • Silver iodide does not dissolve in ammonia
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11
Q

Describe and explain the trend in reducing ability in Group 7.

A
  • Increases down group
  • More electron shells
  • Larger atomic radius
  • Less electrostatic attraction
  • Easier to remove an electron
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12
Q

What is a reducing agent, in terms of electrons?

A

Electron donor/loses electrons

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13
Q

What kind of reactions occur when fluoride and chloride ions react with concentrated sulfuric acid?

A

Acid-base

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14
Q

Write down the equation for a recation between NaF (or Cl) and concentrated sulfuric acid.

Include state symbols.

A

NaF (s) + H2SO4 (l) –> NaHSO4 (s) + HF (g)

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15
Q

Describe what you would see when NaF (or Cl) reacts with concentrated sulfuric acid.

A

Steamy white fumes (of HF or HCl)

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16
Q

Write down the equations for a reaction between NaBr and concentrated sulfuric acid.

Include state symbols.

A
  1. NaBr (s) + H2SO4 (l) –> NaHSO4 (s) + HBr (g)
  2. 2H+ + 2Br- + H2SO4 (l) –> Br2 (g) + So2 (g) + 2H2O (l)
17
Q

Describe (physically) the products of the reaction between NaBr and concentrated H2SO4.

A

White steamy fumes (of HBr)
Orange fumes (of Br2)
Colourless, acidic gas (SO2)

18
Q

Write down the equations for the reaction between NaI and concentrated H2SO4.

Include state symbols.

A
  1. NaI (s) + H2SO4 (l) –> NaHSO4 (s) + HI (g)
  2. 2H+ + 2I- + H2SO4 (l) –> I2 (s) + SO2 (g) + 2H2O (l)
  3. 6H+ + 6I- + H2SO4 –> 3I2 (s) + S (s) + 4H2O (l)
  4. 8H+ + 8I- + H2SO4 –> 4I2 (s) + H2S (g) + 4H2O (l)
19
Q

Describe (physically) the products of the reaction between NaI and concentrated sulfuric acid. (6)

A

White steamy fumes (HI)
Black solid (I2)
Purple fumes (I2)
Colourless, acidic gas (SO2)
Yellow solid (S)
Gas with bad egg smell (H2S)

20
Q

What is a disproportionation reaction?

A

Where an element is both oxidised and reduced.

21
Q

Write an equation for the reaction of gaseous chlorine with water, without the presence of sunlight.

Include state symbols

A

Cl2 (g) + H2O (l) <–> HClO (aq) + HCl (aq)

22
Q

Write an equation for the reaction of gaseous chlorine with water, with the -presence of sunlight.

Include state symbols.

A

2Cl2 (g) + 2H2O (l) –> 4H+ + 4Cl- + O2

23
Q

Write an equation for the reaction of Cl2 with cold, dilute, aquaeous NaOH, and describe the use of the products of this reaction.

Include state symbols.

A

Cl2 (aq) + NaOH (aq) –> NaCl (aq) + NaClO (aq) + H2O (l)
NaCl and NaClO are used in conjuction as a bleach and disinfectant to kill bacteria.

24
Q

What occurs when Cl2 reacts with KBr?

Equation (state symbols) + observations

A

Cl2 (aq) + 2K+ (aq) + 2Br- (aq) –> 2K+ (aq) +2Cl- (aq) + Br2 (aq)

Yellow solution (due to Br2)

25
Q

Describe fluorine at room temperature.

A

Very pale yellow gas
Highly reactive

26
Q

Describe chlorine at room temperature.

A

Greenish gas, poisonous in high concentrations
Reactive

27
Q

Describe bromine at room temperature.

A

Red liquid, that gives poisonous orange/brown fumes

28
Q

Describe iodine at room temperature.

A

Shiny grey solid which sublimes to purple gas