Name: Allotropes of Sulphur
Uploaded: 2019-07-19
Duration: 6 min 39 s
Description: Sulphur is one of the most useful non-metals which has wide applications in our industries. Watch this video to learn about the important allotropes of sulphur.

Question

How is sulphur dioxide prepared in the laboratory? State its two physical and three chemical properties with equations.

Accepted Answer

Preparation of sulphur dioxide by laboratory method :

Principle : Sulphur dioxide is prepared by heating conc.sulphuric acid with copper turnings.

$Cu + 2 H_{2} {SO}_{4} \to {CuSO}_{4} + 2 H_{2} O + {SO}_{2}$

Description : Copper turnings are taken in a round bottomed flask fitted with a thistle funnel and a delivery tube bent twice at right angles. The flask is clamped to a stand and placed on a wire gauze.

Concentrated sulphuric acid is poured through the thistle funnel so that the end of the funnel file in the acid. On heating the flask sulphur dioxide is evolved.

The gas is heavier than air and soluble in water, so it is collected in gas jars by upward displacement of air. The gas is dried by passing through concentrated sulphuric acid.

Physical properties of sulphur dioxide :

Sulphur dioxide is a colourless gas with suffocating smell of burning sulphur and is poisonous.

It is readily soluble in water. About 80 litres of the gas dissolve in one litre of water at ordinary temperature.

Chemical properties of sulphur dioxide :

Sulphur dioxide is highly double in water and its solution is acidic due to the formation of unstable sulphurous acid.

${SO}_{2} + H_{2} O ⇌ H_{2} {SO}_{3}$

Sulphur dioxide reacts with basic oxides and alkalis forming sulphates

$CaO + {SO}_{2} \to {CaSO}_{3} 2 NaOH + {SO}_{2} \to {Na}_{2} {SO}_{3} + H_{2} O$

Sulphur dioxide oxidises $HI$ to iodine.

$4 HI + {SO}_{2} \to 2 H_{2} O + S + 2 I_{2}$

How is sulphur dioxide prepared in the laboratory? State its two physical and three chemical properties with equations.

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