Question

The industrial manufacture of sulfuric acid is carried out by the :

• A. Haber process
• B. Contact process
• C. Ostwald process
• D. Solvay process

Answer 1

Answer:

B. Contact process

Contact Process

• The Contact Process is the standard industrial method used today for the large-scale production of high-concentration sulfuric acid (H₂SO₄).

• This process replaced the older Lead Chamber Process because it produces a higher concentration of acid (up to 98-99%).

Key Reaction Stages

• Step 1: Production of Sulfur Dioxide (SO₂): Sulfur or sulfide ores (like iron pyrites) are burnt in air to produce sulfur dioxide.

• Step 2: Conversion to Sulfur Trioxide (SO₃): Sulfur dioxide is oxidized by air to sulfur trioxide.

  • This reaction is reversible and exothermic.

  • It requires a catalyst, typically Vanadium Pentoxide (V₂O₅).

  • Optimal conditions include a temperature of approximately 400-450°C and a pressure of 1-2 atmospheres.

• Step 3: Absorption: Sulfur trioxide is absorbed into concentrated sulfuric acid to produce Oleum (pyrosulfuric acid, H₂S₂O₇).

• Step 4: Dilution: The oleum is then diluted with water to produce the desired concentration of sulfuric acid.