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Chemistry > Group 7 > Flashcards

Group 7 Flashcards

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1
Q

Most electronegative element in group 7

A

Fluorine

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2
Q

What intermolecular forces exist in halogen molecules?

A

Van der Waals

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3
Q

State and explain the trend in boiling point down group 7 (5)

A

Increases
Simple molecular structure
Molecule gets bigger down group 7 so increased number of electrons so stronger van der Waals between molecules
Takes more energy to overcome

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4
Q

State and explain the trend in oxidising ability from F2 to I2 (4)

A

Going down the group the halogens become weaker oxidising agents
Oxidising agents are themselves reduced and, therefore, gain electrons.
Going down the group the halogens increase in size and atoms have more shielding, which makes the attraction to incoming electrons weaker
Accept electrons more easily

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5
Q

What colour is fluorine in an aqueous solution

A

Pale yellow gas

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6
Q

What colour is chlorine in an aqueous solution

A

Pale green

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7
Q

What colour is bromine in an aqueous/polar solution

A

Aqueous: yellow/brown
Non polar: orange/brown

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8
Q

What colour is iodine in an aqueous/polar solution

A

Aqueous: brown
Non polar: purple/solid black

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9
Q

State and explain the trend in reducing ability of the halide ions (4)

A

Going down the group, halides become stronger reducing agents
This is because the ions become larger and lose their electrons more easily as the outer electrons are more shielded and further from the nucleus

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10
Q

Write an equation for the reaction of solid sodium fluoride and concentrated H2SO4

A

NaF(s) + H2SO4(aq) —> NaHSO4 (s) + HF(g)

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11
Q

What is observed in the reaction between solid sodium fluoride and concentrated H2SO4

A

steamy white fumes of hydrogen fluoride gas released

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12
Q

Write an equation for the reaction of solid sodium chloride and concentrated H2SO4

A

NaCl(s) + H2SO4(aq) —> NaHSO4(s) + HCl(g)

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13
Q

What is observed in the reaction between solid sodium chloride and concentrated H2SO4

A

steamy white fumes of hydrogen chloride gas released

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14
Q

Write an equation for the reaction of solid sodium bromide and concentrated H2SO4

A

NaBr(s) + H2SO4(aq) —> NaHSO4 (s) + HBr(g)

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15
Q

Write the overall equation for the reaction of bromide ions in HBr and concentrated H2SO4

A

2H+ + H2SO4 +2Br- —> SO2 + 2H2O + Br2

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16
Q

What is observed in the reaction between solid sodium bromide and concentrated H2SO4

A

acidic gas/colourless, choking fumes of SO2 gas
brown fumes of bromine gas

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17
Q

Name the products formed when solid sodium iodide reacts with concentrated sulfuric acid and state the observations you would make upon their formation

A

Steamy fumes of HI
Black solid of iodine, I2
Bad egg smell caused by hydrogen sulphide, H2S gas
Yellow solid of sulphur, S
Colourless solution of sodium hydrogen sulphate, NaHSO4

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18
Q

Write the overall equation for the reaction of iodide ions reducing sulphur from (+6) in H2SO4 to (+4) in SO2

A

2H+(aq) + 2I-(aq) + H2SO4(aq) —> I2(s) + SO2(g) + 2H2O(l)

19
Q

Write the overall equation for the reaction of iodide ions reducing sulphur from (+6) in H2SO4 to (0) in S

A

6H+(aq) + H2SO4(aq) + 6I- (aq) —> S(s) + 4H2O(l) + 3I2(s)

20
Q

Write the overall equation for the reaction of iodide ions reducing sulphur from (+6) in H2SO4 to (-2) in H2S

A

8H+(aq) + H2SO4(aq) + 8I-(aq) —> H2S(g) + 4H2O(l) + 4I2(s)

21
Q

Why is dilute nitric acid added before the silver nitrate?
Why not HCl?

A

To remove any carbonate and hydroxide ions which may be present in the sample which could form Ag2CO3. This is a white precipitate which would give a false positive
HCl would add Cl - ions giving a false positive

22
Q

Describe the test for halide ions

A

Add nitric acid then silver nitrate
Add dilute ammonia to the mixture
Add concentrated ammonia to the mixture

23
Q

Observation with fluoride ions with silver nitrate

A

No visible change

24
Q

Observation with chloride ions with silver nitrate

A

White precipitate forms
AgCl

25
Q

Observation with bromide ions with silver nitrate

A

Cream precipitate forms
AgBr

26
Q

Observation with iodide ions with silver nitrate

A

Yellow precipitate forms
AgI

27
Q

Observation with chloride ions with dilute ammonia

A

White precipitate dissolves

28
Q

Observation with bromide ions with dilute ammonia

A

Cream precipitate remains

29
Q

Observation with iodide ions with dilute ammonia

A

Yellow precipitate remains

30
Q

Observation with chloride ions with concentrated ammonia

A

White precipitate dissolves

31
Q

Observation with bromide ions with concentrated ammonia

A

Cream precipitate dissolves

32
Q

Observation with iodide ions with concentrated ammonia

A

Yellow precipitate remains

33
Q

Equation for reaction of chlorine with water

A

Cl2(g) + H2O(l) —> HClO(aq) + HCl(aq)

34
Q

What is disproportionation?

A

Same species is both oxidised and reduced

35
Q

Equation for reaction of chlorine with water in bring sunlight

A

2Cl2(g) + 2H2O(l) —> 4HCl(aq) + O2(g)

36
Q

Equation for reaction of sodium chlorate with water

A

NaClO(s) + H2O —> Na+(aq) + OH-(aq) + HClO(aq)

37
Q

Equation for reaction of chlorine with cold, dilute, aqueous NaOH

A

Cl2(g) + 2NaOH(aq) —> NaClO(aq) + NaCl(aq) + H2O(l)

38
Q

What type of reaction occurs between sodium halide and sulfuric acid?

A

Acid-base reaction

39
Q

Outline a test for ammonium ions.

A

Add sodium hydroxide solution to the sample and warm it
If the resultant gas turns damp red litmus paper blue it indicates ammonium ions were present in the initial sample

40
Q

Outline a test for hydroxide ions

A

Universal indicator will turn dark blue or purple in the presence of hydroxide ions.

41
Q

Outline a test for carbonate ions.

A

Add a dilute acid to the sample
Bubble the resultant gas through limewater
If it turns cloudy it indicates that carbonate ions were present in the initial sample

42
Q

Even though chlorine is toxic, why do we add it to swimming pools?

A

Adding chlorine to swimming pools kills bacteria
The health benefits of adding very small amounts of chlorine to water outweigh the risks.

43
Q

Give a common use of sodium hypochlorite.

A

Sodium hypochlorite is often used as a disinfectant as it kills bacteria.

Chemistry (28 decks)

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