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Chemistry A Level > Group 7 > Flashcards

Group 7 Flashcards

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1
Q

Fluorine at room temperature

A
  • Yellow poisonous gas
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2
Q

Chlorine at room temperature

A
  • Green poisonous gas
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3
Q

Chlorine in aqueous solution

A
  • Pale green solution / colourless in low concentrations
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4
Q

Bromine at room temperature

A

Brown vapour or red/brown liquid

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5
Q

Bromine in aqueous solution

A
  • Orange solution
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6
Q

Iodine at room temperature

A

Grey / black solid sublimes to purple vapour

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7
Q

Iodine in aqueous solution

A
  • Brown solution
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8
Q

Reaction of chlorine with water to form chloride ions and chlorate (I) ion

A

Cl2 + H2O —> HCl + HClO

Gives bleaching power of wet chlorine

Disproportionation reaction

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9
Q

Chloric (I) acid to make chlorate ions equation

A

HClO + H2O —> ClO- + H3O+ or H+

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10
Q

Chlorine and water in sunlight equation

A

2Cl2 + 2H2O —> 4HCl + O2

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11
Q

Chlorine with cold dilute NaOH equation

A

Cl2 + NaOH —> NaCl + NaClO + H2O

Sodium chlorate used as bleach

Disproportionation reaction

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12
Q

What can HCl and HClO be used for?

Why can Cl2 be used since it’s toxic?

A
  • Both kill bacteria in drinking water or swimming pools in low concentrations
  • Cl2 used as benefits outweigh the potential health risks to humans
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13
Q

Why are fluoride ions added to water?

A

To prevent tooth decay as they strengthen enamel

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14
Q

Chlorine with NaBr ionic equation and results

A
  • Cl2 + 2Br- —> Br2 + 2Cl-
  • Br2 released so orange colour observed
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15
Q

Chlorine with NaI ionic equation and results

A
  • Cl2 + 2I- —> I2 + 2Cl-
  • Brown colour observed
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16
Q

Bromine with NaCl and NaBr

A

No reaction

17
Q

NaCl with Cl2

A

No reaction

18
Q

Bromine with NaI ionic equation and results

A
  • Br2 + 2I- —> I2 + 2Br-
  • Brown colour observed
19
Q

Iodine with NaCl, NaBr or NaI

A

No reaction

20
Q

Strength of oxidising agent down group 7

A

Decreases down, iodine is the weakest oxidising agent because fluorine smallest ion so electrons most strongly held by the nucleus compared to other ions / less shielding

21
Q

Reduction equation of Cr2O7(2-)

A

Cr2O7(2-) + 6e- + 14H+ —> 2Cr(3+) + 7H2O

22
Q

Reduction equation of MnO4

A

MnO4 + 5e- + 8H+ —> Mn2+ + 4H2O

23
Q

Reduction equation of MnO2

A

MnO2 +2e- + 4H+ —> Mn2+ +2H2O

24
Q

Reduction equation of H2SO4 to SO2

A

H2SO4 + 2e- + 2H+ —> SO2 + 2H2O

25
Q

Colour change of KMnO4 if reduction has occured

A
  • Purple solution will turn pink (or colourless with a dilute solution)
26
Q

Colour change of K2Cr2O7 is reduction has occured

A
  • Orange solution turns green
27
Q

S(2-) to SO4(2-) oxidising equation

A

S2- + 4H20 —> SO4(2-) + 6e- + 8H+

28
Q

Test for HCl, HBr and HI

A

Damp blue litmus paper will turn red

  • All hydrogen halides produce white misty fumes
29
Q

Reaction of H2SO4 and sodium halide equation and which react further

A
  • H2SO4 + NaCl —> NaHSO4 + HCl
  • H2SO4 + NaF —> NaHSO4 + HF
  • H2SO4 + NaBr —> NaHSO4 + HBr
  • H2SO4 + NaI —> NaHSO4 + HI

Only NaBr and NaI react further as they are strong enough reducing agents and can reduce sulfuric acid

30
Q

Strength of reducing agents down the group

A
  • Increases down group
  • Iodine strongest reducing agent and fluorine the weakest
31
Q

NaBr + H2SO4 full overall equation

A

2NaBr + 3H2SO4 —> 2NaHSO4 + SO2 + 2H2O + Br2

32
Q

NaBr + H2SO4 ionic equation

A

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

33
Q

Why are there 3 potential reactions with NaI and H2SO4

A

I- is a stronger reducing agent

34
Q

Give the ionic equation and full equation of the reaction with H2SO4 that gives a pruple vapour (I2) and black solid (I2)

A
  • 2I- + H2SO4 + 2H+ —> I2 + SO2 + 2H2O
  • 2NaI + 3H2SO4 —> 2NaHSO4 + SO2 + 2H2O + I2
35
Q

Give full equation and ionic equation for reaction with H2SO4 that produces a yellow solid

A
  • 6I- + H2SO4 + 6H+ —> 3I2 + S + 4H2O
  • 6NaI + 7H2SO4 —> 6NaHSO4 + S + 4H2O + 3I2
36
Q

Give the full equation and ionic equation of reaction with H2SO4 that produces a rotten egg smell

A
  • 8I- + H2SO4 + 8H+ —> H2S + 4I2 + 4H2O
  • 8NaI + 9H2SO4 —> 8NaHSO4 + H2S + 4H20 + 4I2
37
Q

Test for H2S

A

With lead nitrate paper makes lead sulfide and nitric acid, so paper goes black as black insoluble compound

  • H2S (g) + Pb(NO3)2 (aq) —> PbS (s) + 2HNO3 (aq)

Chemistry A Level (25 decks)

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