Chapter 16:Sulphuric acid 

Sulphuric acid

• Sulfuric acid or sulphuric acid is a mineral acid composed of the elements sulfur, oxygen and hydrogen.

Oxides of Sulphur

• There are two main oxides of Sulphur
  • [ ] Sulphur Dioxide (So2): gas formed when sulphur burns in air
  • [ ] Sulphur trioxide(So3): involves the catalytic oxidation of sulphur dioxide which is carried out industrially in the Contact process.

Industrial manufacture of Sulphuric acid

• Preparation of sulphur dioxide.

• .Conversion of sulphur dioxide into sulphur trioxide.

• Conversion of sulphur trioxide formed into concentrated H2SO4.

• Step 1: Preparation of sulphur dioxide:

• [ ] SO2 is prepared by burning sulphur in the presence of excess air so that the product combines with oxygen which is helpful for the next stage.

• [ ] S(s) + O2 (g) → SO2(g)

• Step 2: Preparation of sulphur trioxide:

• [ ] Sulphur trioxide is formed when sulphur dioxide reacts with oxygen in a ratio of 1:1

• [ ] at a temperature of 400 °C – 450°C

• [ ] and a pressure of 1-2 atm in the presence of V2O5 as a catalyst.

• [ ] This reaction is reversible in nature.

• [ ] 2SO2(g) + O2(g) ⇌ 2SO3(g)

• Step 3: Preparation of concentrated sulphuric acid:

• [ ] The sulphur trioxide formed is first made to react with concentrated sulphuric acid.

• [ ] H2SO4 + SO3(g) → H2S2O7(l)

• [ ] H2S2O7(l) + H2O(l) → 2H2SO4

Uses of Sulphuric Acid

• In Industries:
  • [ ] used in the production of phosphoric acid which is in turn used to make phosphate fertilizers.
  • [ ] It is used in the manufacturing of metals such as copper, zinc etc.
  • [ ] making of fibres.
  • [ ] Used in acidic drain cleaners.
  • [ ] Used as a catalyst in the manufacturing process of nylon.
  • [ ] Used in the Manheim process in the manufacturing of HCl.
• Used in petroleum refining.

Acid rain

• Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air.
• These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.