Preparation & Properties of Compounds

Questions & Answers

Conc. H2SO4 cannot be used for drying H2. Explain

Q: Conc. H2SO4 cannot be used for drying H2. Explain

Sol: Hydrogen, sometimes, ignites the large amount of heat released when water is absorbed by acid.

In the manufacture of sulphuric acid by the contact process, sulphur trioxide is not directly dissolved in water. Why?

Q:  In the manufacture of sulphuric acid by the contact process, sulphur trioxide is not directly dissolved in water. Why?

Sol:  SO3 reacts with water to form H2SO4 which is not easily condensed and escapes in the atmosphere. It is therefore, absorbed in conc. H2SO4 to form oleum which may be diluted to form H2SO4.

H2SO4 + SO3 → H2S2O7

H2S2O7 + H2O → 2H2SO4

Why H2S is stronger acid than H2O ?

Q:  Why H2S is stronger acid than H2O ?

Sol:  The H – S bond is weaker than H – O bond and the proton is easily released when H2S reacts with water.

Why dry SO2 does not bleach dry flowers?

Q: Why dry SO2 does not bleach dry flowers ?

Sol:  Nascent hydrogen is responsible for bleaching, according to the following reaction

SO2 + 2H2O → H2SO4 + 2H

Coloured flower + H → Colourless flower

Ferric iodide is very unstable but ferric chloride is stable. Why?

Q:  Ferric iodide is very unstable but ferric chloride is stable. Why?

Sol: I is a strong reducing agent. Iodide thus reduces ferric ion into ferrous ion. Cl is a weak reducing agent hence doesn’t reduces Fe+3 to Fe+2.