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CHEMISTRY - inorganic > AS - group 7 > Flashcards

AS - group 7 Flashcards

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1
Q

What colour is fluorine?

A

pale yellow gas

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2
Q

what colour is chlorine?

A

yellow green gas

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3
Q

what colour is bromine?

A

dark red liquid

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4
Q

what colour is iodine?

A

shiny grey-black solid

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5
Q

What happens to the melting points of group 7 and why?

A

They increase as molecules get larger they have more electrons, so have stronger van der Waals so more energy is required to overcome

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6
Q

What happens to the electronegativity and why?

A

decrease as outer electrons are further from the nucleus and there is more shielding so less attraction

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7
Q

What ions would fluorine displace?

A

Cl-, Br-, I-

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8
Q

What ions would chlorine displace?

A

Br-, I-

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9
Q

What ions would bromine displace?

A

I-

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10
Q

What ions would iodine displace?

A

none

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11
Q

What colour would the solution turn if chlorine, bromine or iodine were present?

A

chlorine - yellow
bromine - orange
iodine - brown

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12
Q

E.g. ionic equation between chlorine and sodium bromide.

A

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

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13
Q

what are example half equations for the displacement between chlorine and sodium bromide?

A

oxidation -
2Br- > Br2 + 2e-
reduction -
Cl2 + 2e- > 2Cl-

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14
Q

What is the strongest oxidising agent and why?

A

F2
-most likely to gain an e-
-smallest atomic radius
-less shielding
-more attraction between e- and nucleus

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15
Q

what is the strongest reducing agent and why?

A

iodide
-lose e- most easily
-largest atomic radius
-more shielding
-less attraction between e- and nucleus

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16
Q

How do you test for halides?

A

acidify with nitric acid and then add silver nitrate

17
Q

When testing for halides, why do you acidify with nitric acid?

A

It reacts with any carbonates to prevent the formation of Ag2CO3, which would give a false result

18
Q

What is the general equation for the test for halides, where X is the halide?

A

AgNO3 (aq) + NaX (aq) > AqX (s) + NaNO3 (aq)

19
Q

What are the results when only silver nitrate has been added?

A

chloride > white ppt
bromide > cream ppt
iodide > yellow ppt

20
Q

What are the results when dilute NH3 has been added?

A

chloride > colourless as soluble
bromide > cream, NVC
iodide > yellow, NVC

21
Q

What are the results when conc. NH3 is added?

A

chloride > NVC, still colourless
bromide > soluble, colourless
iodide > NVC

22
Q

What are the observations and their causes when potassium chloride reacts with conc. sulfuric acid?

A

misty fumes > displacement of CL-
Universal indicator goes red/orange

23
Q

what is the equation when KCl reacts with H2SO4? Is it a redox and why?

A

H2SO4 + KCl > HCL + KHSO4
not a REDOX as oxidation states of halide and sulfur stay the same

24
Q

What are the observations and their causes when potassium bromide reacts with conc. sulfuric acid?

A

misty fumes > displacement of Br-
brown vapour > oxidation of Br-
colourless gas > reduction of H2SO4
potassium dichromate paper goes green > SO2 made

25
Q

What are the equations when KBr reacts with H2SO4?

A

H2SO4 + KBr > HBr + KHSO4
HBr - reducing agent
2HBr + H2SO4 > SO2 + Br2 + 2H2O

26
Q

What are the observations and their causes when potassium iodide reacts with conc. sulfuric acid?

A

misty fumes > displacement of I-
purple vapour > oxidation of I-
colourless gas > reduction of H2SO4
yellow solid - sulfur
bad egg smell > H2S
potassium dichromate paper goes green > SO2

27
Q

What are the equations when KI reacts with H2SO4?

A

H2SO4 + KI > HI + KHSO4
2HI + H2SO4 > SO2 + I2 + 2H2O
8HI + H2SO4 > H2S + 4I2 + 4H20
6HI + H2SO4 > S + 3I2 + 4H2O

28
Q

Why is chlorine used in swimming pools?

A

to kill bacteria

29
Q

What is the equation when chlorine is added to swimming pools?

A

Cl2 (g) + H2O <> HOCl (aq) + HCl (aq)

30
Q

When chlorine is added to the swimming pools, has it been oxidised or reduced?

A

both, it undergoes disproportionation

31
Q

What is the equation when chlorine is added in sunlight?

A

2Cl2 (g) + 2H2O (l) > 4HCl (aq) + O2 (g)

32
Q

What is added due to the fact in sunlight, chlorine is rapidly lost? what is the equation?

A

solid sodium chlorate (I)
NaClO (s) + H2O <> Na+ (aq) + OH- (aq) + HClO (aq)

33
Q

why are swimming pools kept slightly acidic?

A

In alkaline solution, eqm moves to the left and HClO is removed as ClO- ions

34
Q

what is the equation when chlorine reacts with cold, dilute NaOH?

A

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

35
Q

what is the ionic equation when chlorine reacts with cold, dilute NaOH?

A

Cl2 (g) + 2OH- > ClO- (aq) + Cl- (aq) + H2O (l)

36
Q

why is chlorine used in pools even though it can be toxic?

A

the health benefits outweigh the risks.

CHEMISTRY - inorganic (2 decks)

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