Lecture - 10
Describe manufacture of sulfuric acid in the Industry.
Answer: Sulfuric acid is manufactured in the contact process, which has several stages:
Stage 1: Making sulfur dioxide, SO2. Most sulfur dioxide is made by burning sulfur in
air:
S(s) + O2(g) → SO2(g)
Stage 2: Making sulfur trioxide, SO3. To do this, sulfur dioxide is reacted with oxygen:
2SO2 + O2 ⇌ 2SO3 (g) ∆H= -196 kJ/mol
Conditions:
Temperature: 450-500oC
Pressure: 2 atmospheres
Catalyst: vanadium penta-oxide (V2O5)
Stage 3: Making sulfuric acid, H2SO4. Sulfur trioxide is absorbed into concentrated
sulfuric acid to make oleum, H2S2O7:
H2SO4(l) + SO3(g) → H2S2O7(l)
Oleum is then carefully diluted to make a concentrated solution of sulfuric acid:
H2S2O7(l) + H2O(l) → 2H2SO4(aq)
Why sulfur trioxide is not directly dissolved in water to make sulfuric
acid?
Answer: When sulfur trioxide (SO3) comes in contact with H2O, H2SO4 is produced.
However, direct reaction between them will produce gaseous H2SO4 which will create a
state of dense fog. That is a hazard for the industries. Besides, getting liquid H2SO4 from
this gaseous H2SO4 by condensation is a tough task.
Write down properties of sulfuric acid?
Answer:
Write down uses of sulfuric acid.
Answer: