Group 7 Physical and Chemical properties Flashcards

1
Q

Fluorine state and colour at room temp

A

Gas
Pale yellow

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2
Q

Chlorine state and colour at room temp

A

Gas
Green

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3
Q

Bromine state and colour at room temp

A

liquid
Brown with orange vapour

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4
Q

Iodine state and colour at room temp

A

Solid
Black/grey with purple vapour

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5
Q

Chlorine colour in solution

A

Colourless

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6
Q

Bromine colour in solution

A

Orange/brown

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7
Q

Iodine colour in solution

A

Dark brown/black

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8
Q

Trend in boiling point in group 7

A

Boiling point increases down the group
Halogen molecules increase in size and have more electrons
Stronger van der waals forces
Require more energy to break the intermolecular forces

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9
Q

Trend in electronegativity for halogens

A

Halogens form more electron shields between bonding pair of electrons and positive nucleus
Electrostatic attraction decreases
So electronegativity decreases

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10
Q

Order of oxidisation of halogens

A

F2
Cl2
Br2
I2

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11
Q

Equation for chlorine sterilising water
No UV light

A

Cl2 + H2O <-> HCl + HClO

Disproportionate reaction
Reduced and oxidised in same reaction

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12
Q

Why is the ClO ion important for sterilising

A

ClO ion oxidises the cell membrane of microbes, killing them

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13
Q

Reaction of Cl2 with cold aqueous NaOH

A

Cl2 + 2NaOH —> NaCl + NaClO + H2O

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14
Q

Why is Cl2 used to sterilise despite toxicity

A

Benefits outweigh risks
Concentration of chlorine is low

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15
Q

Chlorine and water reaction
IN UV LIGHT

A

2Cl2 + 2H2O —> 4HCl + O2

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16
Q

identify metal halide of Fluoride + colour/observation and solubility

A

Ag+(aq) + F-(aq) —> AgF (aq)

No observation, silver fluoride soluble in water
No precipitate formed

17
Q

Identify metal halide of Chlorine + colour and solubility

A

Ag+ + Cl- —> AgCl (s)

White precipitate
Soluble in NH3

18
Q

Identify metal halide of Bromine + colour and solubility

A

Ag+ + Br- —> AgBr (s)
Cream precipitate
Soluble in excess NH3

19
Q

Identify metal halide of Iodine + colour and solubility

A

Ag+ + I- —> AgI (s)
Yellow precipitate
Insoluble in NH3

20
Q

What are the spectator ions when identifying metal halides with silver ion

A

Na+
NO3-

21
Q

Why should the silver nitrate solution be acidified when testing for metal halides

A

Prevent formation of Ag2CO3 which can form white precipitate, confusing the results

22
Q

What are the disadvantages of using chlorine as a sterilising agent

A

Some people are allergic
Wasteful - most potable water isn’t used for drinking