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QJEEAdv22Ch27a7: JEE Advanced 2022 Chemistry - Class 11 JEEAdv22Ch27a7 Solution: The treatment of an aqueous solution of of with excess KI…

The treatment of an aqueous solution of 3.74 g3.74 \mathrm{~g} of Cu(NO3)2\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2} with excess KI results in a brown solution along with the formation of a precipitate. Passing H2 S\mathrm{H}_{2} \mathrm{~S} through this brown solution gives another precipitate X\mathbf{X} . The amount of X\mathbf{X} (in gg ) is ___________.

[Given: Atomic mass of H=1, N=14,O=16, S=32, K=39,Cu=63,I=127\mathrm{H}=1, \mathrm{~N}=14, \mathrm{O}=16, \mathrm{~S}=32, \mathrm{~K}=39, \mathrm{Cu}=63, \mathrm{I}=127 ]

Step-by-Step Verified Solution

Number of moles of Cu(NO3)2=3.74187=0.02

2Cu(NO3)20.02+4KI→Cu2I2↓+I20.01+4KNO3

I20.01+KI→KI30.01(Brownsolution)

KI30.01+H2S→KI+S0.01(X)↓+2HI

Number of moles of sulphur precipitated (X) = 0.01

Mass of sulphur precipitates (X) = 0.01 × 32 = 0.32 gm

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