The Preparation and The Preparation and Collection Of Non-Collection Of Non-

Metals.Metals.Ashvini Jagassar- 5C

Chemistry.Mr. Dookoo

Section B- Descriptive Section B- Descriptive ChemistryChemistry

B.2. Inorganic B.2. Inorganic ChemistryChemistry

Preparation and Collection of Non-Metals:

3.1 describe the industrial preparation of chlorine,

sulphuric acid and ammonia;

The Preparation and Collection Of Chlorine.

The main method for the manufacture of chlorine is The Flowing Mercury Cathode Cell. Sodium hydroxide and hydrogen are co products . This is the electrolysis of brine (aqueous sodium chloride) using a continuously flowing mercury cathode and a graphite or titanium anode. The raw material used is concentrated sodium chloride solution (NaCl). The power requirement is approximately 4.5 V, 300,000 A, and the process is carried out at a pH of about 4.5.

The Flowing Mercury Cathode Cell.

Reactions involved in the Electrolysis of Chlorine.

• Cl is discharged at the anode because it is of higher concentration than OH-

2Cl-(aq) - 2e- Cl2(g)

Chlorine gas produced is collected.• At the cathode Na+ is discharged

because of the mercury cathode. The normal order of discharge is reversed on a fresh metal surface (mercury).

Na+ + e- Na(s)

The Preparation and Collection of Sulphuric Acid.

Sulphuric acid is widely manufactured using the Contact Contact ProcessProcess. This process can be divided into three stages:

• The production of sulphur dioxide.Mainly by burning sulphur in air

S(s) + O2(g) SO2(g)

• Oxidation of sulphur dioxide to sulphur trioxide.

Pure dry sulphur dioxide and oxygen are heated to 450oC and passed over a vanadium (V) oxide in silica gel catalyst.vanadium (V) oxide in silica gel catalyst.

2SO2(g) + O2(g) 2SO3(g)

• Hydration of sulphur trioxide.Sulphur trioxide is hydrated indirectly by

initially dissolving in concentrated sulphuric acid. Oleum is formed which is diluted to give concentrated sulphuric acid.

H2SO4(aq) + SO3(g) H2S2O7(aq)

OleumH2S2O7(aq)_ + H2O(l) 2H2SO4(aq)

The Contact Process

The Preparation and Collection of Ammonia.

Ammonia is commercially manufactured by the Haber Process. In this process a purified nitrogen/hydrogen mixture is compressed to 200-350 atm and passed over a finely divided iron catalyst. The heat evolved during the reaction maintains the optimum reaction temperature, 350-400oC.

N2(g) + 3H2(g) 2NH3(g)

The gases leaving the reaction chamber contain 10-20% ammonia, which is removed by condensation under refrigeration or absorption by water. Uncombined nitrogen and hydrogen are recycled.

200-350 atm

350-400oC

Iron catalyst

Preparation of Ammonia Gas.