The document provides information about chlorine and hydrogen chloride. It discusses the preparation of chlorine using various oxidizing agents like manganese dioxide and potassium permanganate. It describes the Deacon's process and electrolytic process for manufacturing chlorine. The physical and chemical properties of chlorine and hydrogen chloride are explained, including their reactions with metals, nonmetals, hydrocarbons and uses of chlorine.

1. The Malegaon High School & Jr. College
Malegaon, (Nashik), 423203
5th Lecture on Elements of
groups 16, 17 & 18
Chemistry Part I, 12th Science
By
Rizwana Mohammad

2. Chlorine and compounds of chlorine:
Chlorine: (Greek, chloros = greenish yellow)
a. Preparation:
1. Chlorine can be prepared by the oxidation of HCl with any of
following oxidising agents.
i. Manganese dioxide:
MnO2 + 4HCl → MnCl2 + Cl2 + 2H2O
ii. Potassium permanganate:
2KMnO4 + 16HCl → 2KCl + 2MnCl2 + 8H2O + 5Cl2
2. Chlorine can also be prepared by the action of conc. H2SO4 on a
mixture of NaCl and MnO2.
4NaCl + 4H2SO4 → 4NaHSO4 + 4HCl
MnO2 + 4HCl → MnCl2 + 2H2O + Cl2
4NaCl + MnO2 + 4H2SO4 → 4NaHSO4 + MnCl2 + 2H2O + Cl2

3. b. Manufacture of chlorine:
i. Deacon’s process:
4HCl + O2 2Cl2 + 2H2O
ii. Electrolytic process:
By the electrolysis of brine, chlorine is liberated at the anode.
NaCl ⇌ Na+ + Cl-
Cathod: 2H2O + 2e- → H2 + 2OH-
Na+ + OH- → NaOH
Anode: Cl- → Cl + e-
Cl + Cl → Cl2
c. Physical properties of chlorine:
i. Chlorine is a greenish yellow gas having pungent and suffocating
odour.
ii. It is poisonous in nature.
iii. It can be easily liquify into a greenish yellow liquid, which boils at
293K.
iv. It dissolves in water to give chlorine water.
v. It is 2-5 times heavier than air.
C Clu 2
723K

4. d. Chemical properties of chlorine:
i. Reaction with metals:
2Al + 3Cl2 → 2AlCl3
2Na + Cl2 → 2NaCl
2Fe + 3Cl2 → 2FeCl3
ii. Reaction with nonmetals:
P4 + 6Cl2 → 4PCl3
S8 + 4Cl2 → 4S2Cl2
iii. Affinity for hydrogen:
H2 + Cl2 → 2HCl
H2S + Cl2 → 2HCl + S
iv. Reaction with NH3:
8NH3 + 3Cl2 → 6NH4Cl + N2
Excess
NH3 + 3Cl2 → NaCl3 + 3HCl
Excess

5. v. Reaction with alkali:
2NaOH + Cl2 → NaCl + NaOCl + H2O
Cold and dilute
6NaOH + 3Cl2 → 5NaCl + NaClO3 + 3H2O
Hot and conc.
2Ca(OH)2 + 2Cl2 → Ca(OCl)2 + CaCl2 + 2H2O
Slaked lime
vi. Reaction with hydrocarbon:
CH4 + Cl2
UV
CH3Cl + HCl
H2C = CH2 + Cl2 →
vii. Oxidising property:
2FeSO4 + H2SO4 + Cl2 → Fe2(SO4)3 + 2HCl
Na2SO3 + Cl2 + H2O → Na2SO4 + 2HCl
SO2 + 2H2O + Cl2 → H2SO4 + 2HCl
I2 + 6H2O + 5Cl2 → 2HIO3 + 10HCl
Cl Cl
1,2 - Dichloroethane

6. viii. Bleaching property:
• Chlorine requires the presence of moisture for bleaching.
• It liberates nascent oxygen from water which is responsible for its
oxidising and bleaching property.
Cl2 + H2O → HCl + HOCl
HOCl → HCl + [O]
• Chlorine bleaches vegetable matter or coloured organic matter in
the presence of moisture to colourless matter.
• Coloured organic matter + [O] → colourless organic matter.

7. e. Uses: Chlorine is used
• For purification (sterilizing) of drinking water.
• For bleaching wood pulp required for manufacture of paper and
rayon, bleaching cotton and textiles.
• For extraction of metals like gold and platinum.
• In the manufacture of dyes, drugs and organic compounds such as
CCl4, CHCl3, DDT, refrigerants etc.
• In the preparation of poisonous gases such as phosgene (COCl2),
tear gas (CCL3NO2), mustard gas (ClCH2CH2SCH2CH2Cl).

8. Hydrogen chloride:
a. Preparation:
NaCl + H2SO4
420K
NaHSO4 + HCl
NaHSO4 + NaCl
420K
Na2SO4 + HCl
b. Physical properties of HCl:
i. HCl is a colourless and pungent smelling gas.
ii. It can be easily liquefied to a colourless liquid (b.p. 189K) which
freezes to a white crystalline solid (m.p. 159K).
iii. It is highly soluble in water.

9. c. Chemical properties:
i. Acidic property:
HCl is highly soluble in water and ionizes as follows:
HCl(g) + H2O(l) → H3O+
(aq) + Cl-
(aq)
Ka = 107
The aqueous solution of HCl gas is called hydrochloric acid. High value
of dissociation constant (Ka) indicates that it is a strong acid in water.
ii. Reaction with NH3:
NH3 + HCl → NH4Cl
white fumes
iii. Reaction with noble metals:
Au + 4H+ + NO3
- + 4Cl-→ AuCl4
- + NO + 2H2O
3Pt + 16H+ + 4NO3
- + 18Cl- → 3PtCl6
2- + 4NO + 8H2O