####48. is a binary compound of a univalent metal. of reacts completely with of sulphur in an evacuated and sealed tube to give of a white crystalline solid , that forms a hydrated double salt, with . Identify and .
(1994, 2M)
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Solution:
- Compound forms hydrated crystals with . Also, is formed with univalent metal on heating with sulphur. Hence, compound must has the molecular formula and compound must be an oxide of which reacts with sulphur to give metal sulphate as
sulphur gives of
(one mole) will give
Therefore, molar mass of
Atomic weight of
Atomic weight of , metal is potassium (K)
on treatment with aqueous gives potash-alum.
If the metal oxide has molecular formula , fwo moles of it combine with one mole of sulphur to give one mole of metal sulphate as
