Group 7 Properties

Question 1

Iodide with silver nitrate

Answer 1

Yellow precipitate

Question 2

Bromide with silver nitrate

Answer 2

Cream precipitate

Question 3

Chloride with silver nitrate

Answer 3

White precipitate

Question 4

Fluoride with silver nitrate

Answer 4

No visible change

Question 5

Equation for reaction between NaCl and H2SO4

Answer 5

NaCl + H2SO4 = NaHSO4 + HCl

Question 6

Observation from reaction between NaCl and H2SO4

Answer 6

White Steamy fumes

Question 7

Equation for reaction between NaBr and H2SO4

Answer 7

NaBr + H2SO4 = NaHSO4 + HBr
2HBr + H2SO4 = Br2 + SO2 + 2H2O
REDOX H2SO4 acts as an acid to produce HBr then an oxidising agent

Question 8

Observation of reaction between NaBr and H2SO4

Answer 8

White Steamy fumes

Red fumes of bromine

Question 9

Equation for reaction between NaI and H2SO4

Answer 9

NaI + H2SO4 = NaHSO4 + HI
H2SO4 acts as an acid in th3e first step to produce HI then as an oxidising agent in the 3 redox steps

2 HI + H2SO4 = I2 + SO2 + 2 H2O
6 HI + H2SO4 = 3 I2 + S + 4 H2O
8 HI + H2SO4 = 4 I2 + H2S + 4 H20

Question 10

Observation of reaction between NaI and H2SO4

Answer 10

White steamy fumes 
Purple fumes
OR
Black Solid
Yellow sulphur solid
Pungent smell

Question 11

Trend in MP and BP in group 7

Answer 11

MP and BP increase down the group

More VDW forces because increasing number of electrons

Question 12

Trend in electronegativity in group 7

Answer 12

Electronegetivity decreases down the group
Increasing atomic radius
distance between nucleus and electrons
less able to attract them in a bond

Question 13

Trend in Oxidising strength in group 7

Answer 13

oxidising strength decreases down the group

Electron acceptor

Question 14

What does the colour of a displacment solution tell you

Answer 14

the colour shows the free or displaced halogen present in solution

Question 15

Trends in displacement in group 7

Answer 15

Chlorine displaces bromide and iodide ions
Bromine will displace iodide
Eg) Cl2 + 2Br- = 2Cl- + Br2

Question 16

Silver Halide reactions with ammonia

Answer 16

Silver chloride dissolves in DILUTE ammonia- colourless solution
Silver bromide dissolves in CONCENTRATED ammonia- colourless solution
Silver iodide doesn’t react with ammonia- too insoluble

Question 17

Trends in halides as reducing agents

Answer 17

Increasing power as a reducing agent down the group
(electron donator)
As ion increases in size FoA decreases because of additional shells making it easy to lose outer electron

Question 18

Sodium Fluoride and chloride reactions with H2SO4

And observation

Answer 18

Not strong enough to reduce S (No REDOX, acid base reaction)
Observe white steamy fumes
NaF + H2SO4 = NaHSO4 + HCl

Question 19

Reduction products of Bromide with H2SO4

Answer 19

Sulfur dioxide

Question 20

Reduction products of Iodide with H2SO4

Answer 20

Sulfur dioxide
Sulfur
Hydrogen sulfide

Question 21

Define disproportionation

Answer 21

a reaction where an element simultaneously oxidises and reduces

Question 22

Chlorine with water (Disproportionation)

Answer 22

Cl2 + H2O = HClO + HCl

if universal indicator added, first turn red due to acidic products, then colourless as HClO bleaches it

Question 23

Chlorate

Answer 23

ClO3 1-

Question 24

Reaction of chlorine with water in bright sunlight

Answer 24

2Cl2 + 2H2O = 4H+ + 4Cl- + O2