Sulfur

Sources sulfur

• By-product of petroleum and natural gas refining
• Occurs in sulphide ores e.g. lead sulphide
• Underground sulfur beds
• Volcano rims

Uses

Sulfur	Sulfur Dioxide
Rubber vulcanization	As a bleach for wood pulp in the manufacture of paper
In car batteries as an electrolyte	Food preservative; kills bacteria
Manufacture of sulphuric acid ( Contact Process)	Metal and ore refining (reducing agent)

Sulphuric acid

Sulphuric acid is a colourless liquid, strong, non-volatile acid. It is a very strong oxidising agent i.e. it can oxidize both metals and non-metals (bases) forming salts (sulphates). Its soluble in water and emits heat when dissolved. It can be used as a dehydrating agent as it absorbs water.

Contact Process

Factors employed to increase yield of Sulphur trioxide

     Temperature- 450 0C (low)
     Pressure- 1atm,
     Catalyst- vanadium(v) oxide (it speeds up the rate of reaction).

Procedure

❶ Formation of Sulphur dioxide

Sulphur is reacted with oxygen to form sulphur dioxide.
S(g) + O₂ → SO₂(s)

 

❷ Formation of Sulphur trioxide

SO₂ is further reacted with oxygen to form sulphur trioxide in a reversible reaction (going both directions).
2SO₂ + O₂(g) ⇋ 2SO₂(g).

 

❸ Formation of oleum

Sulphur trioxide is cooled and reacted in concentrated sulfuric acid to produce oleum,
SO₃ + H₂SO₄ → H₂S₂O₇.
When sulfur trioxide is reacted with water it forms a mist sulfuric acid.

❹ Formation of Sulfuric Acid

Oleum is diluted with water to form sulphuric acid.

H₂S₂O₇ + H₂O → 2H₂SO₄

 

Properties of Sulfuric Acid

• • Concentrated H₂SO₄  is a strong oxidizing and dehydrating agent
  • Corrosive when concentrated
  • Low pH (turns blue litmus red)
  • High electrical conductivity

 

Uses of Sulphuric acid

Concentrated	Diluted
Used in phosphate fertilizers	Cleaning metal surfaces
Production of paints and dyes	Catalyst in organic reactions

• in making detergents
• to manufacture plastics and fibres
• in refining petroleum
• as electrolyte in car battery
• galvanization and electroplating
• in production of dyes, drugs, explosives…