Same chapter3 marksDifficulty: Medium
Why must concentrated sulphuric acid always be added to water and never water to the acid?
Study of Compounds: Sulphuric Acid
2 marksDifficulty: Medium
What is oleum and why is sulphur trioxide dissolved in sulphuric acid rather than in water?
Original Khojo Papers practice question — not from a past board paper.
Answer
Oleum is fuming sulphuric acid, H2S2O7, formed when sulphur trioxide is absorbed in concentrated sulphuric acid. Sulphur trioxide reacts with water so violently that a dense mist of acid droplets is formed which is difficult to condense, so the indirect route is used.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
The oleum is later diluted with the right amount of water to give sulphuric acid of any required strength.
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