GRP 17

Question 1

Comment on solubility of halogens in water

Answer 1

-halogens are insoluble in water
-weak dipole-dipole interactions are formed b/w halogen and water molecules
-insufficient amt of energy is released to overcome strong intermolecular hydrogen bonds b/w water molecules for hydration to occur

Question 2

Comment on solubility of halogens in organic compounds(eg hexane)

Answer 2

-halogens are soluble in organic solvents
- idid int of comparable strength formed b/w hexane and halogen molecules release sufficient energy to overcome idid int in halogen and organic solvent
-allowing halogen and organic solvent molecules to intermingle and dissolve

Question 3

Explain volatility of halogens down the group

Answer 3

-volatility ↓ down grp
-halogens are simple molecules w/ weak idid int b/w halogen molecules
-down the grp, no. of e ↑, greater momentary polarisation of e-cloud
-strength of intermolecular idid↑
-↑amt of energy req to overcome stronger idid int
-BP and MP ↑, volatility ↓

Question 4

Explain oxidising power of halogens down group(theory)

Answer 4

-[O] power ↓ down grp
-no. of filled PQS↑ down grp, valence e- are increasingly further away from nucleus and are less strongly attracted to nucleus
-ability of atom to attract bonding electrons↓, electronegativity↓ down grp

Question 5

Explain oxidising power of halogens down group(using E°)

Answer 5

-Down the grp, E° becomes less positive.
-ability of halogens to be reduced↓
-ability to oxidise other species ↓
-oxidising power of halogens ↓

Question 6

Explain reactivity of halogens with hydrogen down the group

Answer 6

-reactivity w/ H2 ↓ down grp
-halogens act as OAs
-oxidising power of halogens decrease down grp, gains e- less readily
-thus rxn with hydrogen is less vigorous

Question 7

Explain thermal stability of hydrogen halides down the group

Answer 7

-thermal stability ↓ down grp
-Bond energy ↓, covalent bond strength↓ thus TS↓

Question 8

Colours of all halogens(all states)

Answer 8

F2: Pale yellow gas
Cl2: Greenish yellow gas, pale yellow aq
Br2: Reddish brown gas/liq, orange aq
I2: Black solid,brown aq, purple gas

Question 9

Colours of all halogens(in hexane)

Answer 9

F2: nil(reacts w/ hexane)
Cl2: pale yellow
Br2: orange-red
I2: purple

Question 10

Eqn of reaction of halogen with sodium thiosulfate(balanced)

Answer 10

S2O32-(aq) + 4X2(Aq) + 5H2O(l) -> 2SO42-(aq) + 10H+(aq) + 8X-(aq)

Question 11

Eqn of reaction of I2 with sodium thiosulfate(balanced)

Answer 11

2S2O32- + I2(aq) -> 2I-(aq) + S4O62-(aq)