JEE Main · 2024 · 05 Apr 2024 · Shift 2 · Equilibrium

While preparing crystals of Mohr's salt, dil.

H_{2} SO_{4}

is added to a mixture of ferrous sulphate and ammonium sulphate, before dissolving this mixture in water, dil.

H_{2} SO_{4}

is added here to:

(A)prevent the hydrolysis of ferrous sulphate✓ Correct
(B)prevent the hydrolysis of ammonium sulphate
(C)make the medium strongly acidic
(D)increase the rate of formation of crystals

Answer: (A)

Solution

F e^{2 +}

readily hydrolyses in aqueous solution (and is prone to aerial oxidation), which would spoil the crystallisation of Mohr's salt. Dilute

H_{2} S O_{4}

is added before dissolving the ferrous sulphate–ammonium sulphate mixture specifically to suppress this hydrolysis of the ferrous sulphate, so that well-formed crystals of

F e S O_{4} \cdot (N H_{4})_{2} S O_{4} \cdot 6 H_{2} O

can be obtained.

JEE Main · 2024 · 05 Apr 2024 · Shift 2 · Single correct option

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JEE Main · 2024 · 05 Apr 2024 · Shift 2 · Equilibrium

Solution

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