Group 7

Question 1

Chlorine
Colour:
State(room temp):
Colour in solution(polar solvent):
Colour is cyclohexane(nonploar solvent):

Answer 1

green
gas
pale green
pale green

Question 2

Bromine
Colour:
State(room temp):
Colour in solution(polar solvent):
Colour is cyclohexane(nonploar solvent):

Answer 2

red-brown
liquid
orange
orange

Question 3

iodine
Colour:
State(room temp):
Colour in solution(polar solvent):
Colour is cyclohexane(nonploar solvent):

Answer 3

black
solid
brown
pink-purple

Question 4

Why are halogens more solvent in non-polar solvents (cyclohexane) than polar solvents(water )

Answer 4

Because halogens are nonpolar

solubility of halogens in water decreases down the group

Question 5

are halogens reducing agents or oxidizing agents and why ? (trend)

Answer 5

Halogens are oxidizing agents because they gain electrons to form halide ions#
oxidizing ability decreases down the group

Question 6

disproportionation of Cl
observations
and equation

Answer 6

Cl2 + H2O  HClO + HCL
If under UV
Cl2 + H2O --> 2HCl + 1/2 O2
Chlorine (pale green solution)
blue litmus turns red (HCl)
Blue litmus gets bleached (HClO)

Question 7

uses of chlorine water in treatment

Answer 7

benefit: Kills bacteria
risk: toxic in large quantities

Question 8

reaction of chlorine and cold dilute sodium hydroxide solution And uses of solution formed

Answer 8

Cl2 + NaOH —> NaCl + NaClO + H2O (disproportionation)
NaClO (sodium chlorinate)
green colour fades and smell becomes less pungent
Bleach & to kill bacteria

Question 9

How to test for Halide ions (Cl-,Br-)

Answer 9

Make solution of substance to be tested
react with dilute nitric acid (To remove other ions that will interlinear)
Add silver nitrate solution observe colour of ppt
Fluoride:No ppt as silver fluoride is soluble in water
chloride:white(silver chloride)
bromide:cream(Silver bromide)
iodide:yellow(Silver iodide)

Question 10

Trends in solubility of silver halide salts

Answer 10

Dilute ammonia: soluble AgCl
Concentrated ammonia: soluble AgCl + AgBr
insoluble : AgI
Equation:
AgCl(s) + NH3(aq) —> (Ag(NH2)2)+1(aq) + Cl-(aq)

Question 11

are halide ions reducing or oxidising agents ?

Answer 11

halide ions are reducing agents because they donate electrons to for halogens

Question 12

possible reduction products of halide ions reacting with sulfuric acid
Compoumd,name,OS of S,appearance

Answer 12

H2SO4 Sulfuric Acid +6
SO2 sulfur dioxide +4 choking gass
S sulfur 0 yellow solid
H2S hydrogen sulfide -2 gas with bad eggs smell

Question 13

Acid base products of H2SO4 reaction with halide salts
NaCl
NaBr
NaI

Answer 13

STEAMY WHITE FUMES FOR ALL
HCl
HBr
HI

Question 14

redocx products of H2SO4 reaction with halide salts & products
NaCl
NaBr
NaI

Answer 14

reduction:
Cl2 (does not redox)
Br2 orange fumes 
I2 black solid(purple vapours)
oxidation:
Cl2(does not redox)
SO2 ((choking gas)
SO2,H2S,S (chocking gas , bad eggs smell ,yellow solid) (all products)

Question 15

Chloride ions reaction with H2SO4

why cant Cl- reduce H2SO3 ?

Answer 15

NaCl + H2SO4 –> NaSO4 + HCl
(no change in OS state for any element)
H2SO4 acts as an acid
chloride cannot reduce H2SO4 as it is a weak reducing agent

Question 16

reducing strength of halide ions as you go down the group

Answer 16

reducing strength increases (as more shielding and shells weaker att to outer most e-)