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CCEA AS Chemistry Units 1, 2 And 3 > (U1) Halogens > Flashcards

(U1) Halogens Flashcards

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1
Q

What colour and state is Fluorine

A

Yellow gas

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2
Q

what colour and state is Chlorine

A

Yellow-Green gas

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3
Q

what colour and state is Bromine

A

Red-Brown liquid

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4
Q

what colour is solid Iodine

A

Grey-Black

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5
Q

what colour is Iodine vapor

A

Purple

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6
Q

what colour is Chlorine water

A

Pale Green/Colourless

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7
Q

what colour is Bromine water

A

Brown

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8
Q

what colour is Iodine in POLAR solvents

A

Yellow-Brown

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9
Q

what colour is Iodine in NON-POLAR Solvents

A

Purple

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10
Q

What is the observation for reactions between:

  • Fluorides and
  • Concentrated Sulfuric Acid

(Not needed as much)

A

Steamy/Misty Fumes (of HF)

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11
Q

What is the observation for reactions between:

  • Chlorides and
  • Concentrated Sulfuric Acid
A

Steamy/Misty Fumes (of HCI)

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12
Q

What are the observations for reactions between:

  • bromides and
  • Concentrated Sulfuric Acid
    (3)
A
  • Steamy/Misty Fumes (HBr)
  • Red-Brown Vapour (Br2)
  • pungent smell (SO2)
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13
Q

What are the observations for reactions between:

  • Iodides and
  • Concentrated Sulfuric Acid
    (7)
A

3 reactions:

1.

  • Steamy/misty fumes (of HI)
    • Purple Vapour (I2)
    • pungent smell (SO2)
    • Yellow solid (S)
    • Smell of Rotten Eggs (H2S)
    • Grey-Black solid (on the sides of the test tube) (I2)
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14
Q

What is the observation for reactions between:

  • solid fluorides and
  • Concentrated phosphoric Acid
A

Steamy/misty fumes (of HF)

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15
Q

What is the observation for reactions between:

  • Chlorides and
  • Concentrated phosphoric Acid
A

Steamy/misty fumes (of HCI)

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16
Q

What is the observation for reactions between:

  • Bromides and
  • Concentrated phosphoric Acid
A

Steamy/misty fumes (of HBr)

17
Q

What is the observation for reactions between:

  • Iodides and
  • Concentrated phosphoric Acid
A

Steamy/misty fumes (of HI)

18
Q

State every reaction between sodium iodide and sulphuric acid in order

A
  • NaI + H2SO4 —> HI + NaHSO4
  • HI + H2SO4 —> SO2 + I2 + 2H2O
  • 6HI + H2SO4 —> S + I2 + 4H2O
  • HI + H2SO4 —> H2S + I2 + H2O

Last 2 reactions occur because iodide ions are greater reducing agents than halides up the group

19
Q

What happens to the oxidising ability of halogens down the group?

A

Oxidising ability decreases

20
Q

What happens to the reducing ability of halides down the group?

A

Reducing ability increases

21
Q

Why are halide ions reducing agents while atoms are oxidising agents? (3)

A
  • ions lose electrons more readily
  • larger atomic radius + greater shielding make this easier
  • also halogen atoms would rather gain electrons than lose (oxidising agents), ions are stable
22
Q

Why are the halogens more soluble in non-aqueous / non polar solvents than in aqueous / polar solvents?

A

like dissolves like

  • halogen molecules and non-polar solvents are both held by Van der Waals forces
  • as a result little energy is required to disrupt the forces and form a solution
  • aqueous solutions contain both Van der Waals and hydrogen bonds —> requires more energy to disrupt
23
Q

Why are the halogens soluble in aqueous / polar solvents?

A

Purely because polar solvents are polar and halogens are non-polar —> opposites attract

24
Q

What colour is Chlorine in non-polar solvents?

A

Pale green - but not colourless

25
Q

What colour is Bromine in non-polar solvents?

A

Brown

26
Q

Give the balanced symbol equation for the reaction between water and chlorine

Give state symbols

Then give the word equation

A
  • Cl2 (g) + H2O(l) —> HCl(aq) + HClO(aq)
  • chlorine + water —> hydrochloric acid + chloric (I) acid (or chlorine water)
27
Q

Give the balanced symbol equation for the reaction between chlorine and cold dilute NaOH

Include state symbols

Then give the ionic equation

A
  • Cl2 (g) + 2NaOH(aq) —> NaCl(aq) + NaClO(aq) + H2O(l)
  • Cl2 (g) + 2OH-(aq) —> Cl-(aq) + ClO-(aq) + H2O (l)
28
Q

Give the balanced symbol equation for the reaction between chlorine and hot (70ºC) concentrated NaOH

Include state symbols

Then give the ionic equation

A
  • 3Cl2 (g) + 6NaOH(aq) —> 5NaCl(aq) + NaClO3 (aq) + 3H2O(l)
  • 3Cl2 (g) + 6OH-(aq) —> 5Cl-(aq) + ClO-3 (aq) + 3H2O (l)
29
Q

What does and Iodate ion (IO-) disproportionate to produce?

A

Iodide (I-) and Iodate (v) (IO4-) ions

30
Q

Why is chlorine added to drinking water?

A

Kills pathogens and prevents spread of disease

31
Q

Why is ozone added to drinking water?

A

Breaks down parasites along with pathogens

32
Q

What are the advantages and disadvantages of using chlorine in drinking water?

Give 2 of each.

A

Advantages:

  • Chlorine is a highly efficient disinfectant
  • Residual chlorine remains in the water —> controls contamination
  • Easy to produce and relatively cheap.
  • Chlorine gas can be compressed.

Disadvantages:

  • Chlorine is poisonous/toxic.
  • Can’t treat all water-borne pathogens while ozone can
  • can react to produce compounds known as disinfection by-products (DBP) which can cause health hazards such as cancer.
  • volatile and not all of it remains dissolved in the water.
  • Can spoil the taste of the water.
  • Chlorine can affect the odour/smell of the water.
  • Storing large quantities of chlorine causes problems.
  • inhibits freedom of choice
33
Q

What are the advantages and disadvantages of using ozone in drinking water?

Give 2 of each.

A

Advantages:

  • Cost effective
  • Greater disinfection effectiveness against bacteria and viruses than chlorination.
  • Has oxidising properties —> lowers the concentration of metals such as iron and manganese by converting them into insoluble metal oxides that can be removed by filtration.
  • Can treat all water-borne pathogens.

Disadvantages:

  • Unstable —> no residual ozone left in the water to control contamination
  • does not remove nitrates or chlorides
  • does not remove hardness from the water
  • inhibits freedom of choice

CCEA AS Chemistry Units 1, 2 And 3 (22 decks)

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