Summary Study / Revision notes - Topic 12 Sulfur - Chemistry CIE IGCSE (A* student)

LUCÍA ROMERO


12. SULFUR

12.1 SULFUR

Characteristics

▪ It is a yellow solid at room temperature
▪ It has a low melting point (115 degrees)

Sources

1. It is produced during the refinement of petroleum
2. In crude oil and natural gas
3. Places like USA, Texas, Ethiopia, Australia

Uses

1) To make sulphuric acid
2) To toughen rubber, in a process called vulcanisation

USES OF SULPHURIC ACID:

I. Car batteries
II. Laboratory acids
III. Fertilisers
IV. Soaps and detergents
V. Paints and dyes

The contact process / making sulfuric acid

Sulphuric acid→ H2SO4

RAW MATERIALS:

1. Sulphur
2. Air
3. Water

STEP 1:

Roast it (the sulphur) in air, to form SULPHUR DIOXIDE

S + O2 → SO2

STEP 2:

Mix it with more air, and pass over 4 separate beds of a catalyst, to form SULPHUR TRIOXIDE

Factors needed:

1. A vanadium oxide (V2O5) catalyst
2. A temperature of 450 degrees
3. Pressure of 1-5 atmospheres

2SO2 + O2 ⇄ 2SO3

STEP 3:

Dissolve the sulfur trioxide in concentrated sulphuric acid, to form OLEUM

SO3 + conc H2SO4 → H2S2O7 (oleum)

Why don’t we put sulfur trioxide directly in water?

Because the direct combination of SO3 with water is too exothermic and forms a fine mist of acid.

STEP 4:

Dilution of oleum (we mix it carefully with water), to get CONCENTRATED SULPHURIC ACID (H2O + H2S2O7 → 2H2SO4)