Question

A crystalline solid ‘A’ burns in air to form a gas 'B' which turns lime
water milky. The gas is also produced as a by-product during roasting of
sulphide ore. This gas decolourises acidified KMnO4 (aq.) solution and
reduces Fe3+ to Fe2+. Identify ‘A’and 'B' and write the reactions involved.​

Answer 1

Answer:

An amorphous solid A burns in air to form a gas B which turns lime water milky. The gas is also produced as a byproduct during roasting of sulphide ore. This gas decolourises acidified aqueous KMn04 solution and reduces Fe3+ to Fe2+. ... Therefore, gas 'S' must be S02.

Explanation:

the amorphous solid A is sulphur (s8) while gas b is sulphur dioxide.

S8 + 8O2 8SO2

The gas SO2 turns the lime water milky.

Roasting of sulphide ore :

2ZnS + 3o22ZnO + 2SO2

Hence sulphur dioxide is produced during the roasting of sulphide ore.

The gas B decolourise the acidified KMnO4 solution and reduces Fe3+ to Fe2+

2KMnO4 + 5SO2 +2H2O K2SO4 + 2MnSO4 + 2H2SO4

Fe(SO4)3 + SO2 + 2H2O 2FeSO4 + 2H2SO4

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