An aqueous solution of $\mathrm{FeSO}_{4}, \mathrm{Al}_{2}\left(\mathrm{SO}_{4}ight)_{3}$ and chrome alum is…
An aqueous solution of $\mathrm{FeSO}_{4}, \mathrm{Al}_{2}\left(\mathrm{SO}_{4}ight)_{3}$ and chrome alum is heated with excess of $\mathrm{Na}_{2} \mathrm{O}_{2}$ and filtered. The materials obtained are:-
A colourless filtrate and a green residue.
A yellow filtrate and a green residue.
A yellow filtrate and a brown residue.
A green filtrate and a brown residue.
Solution
The yellow filtrate contains sodium chromate obtained by the oxidation of Cr (III) ion with sodium peroxide.
The brown residue is of basic ferric sulphate $\left(\mathrm{Fe}(\mathrm{OH})\left(\mathrm{SO}_4ight)ight)$ which is obtained by the oxidation of ferrous sulphate with sodium peroxide.
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