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JEE Advanced 2020Paper 2
Exam
JEE Advanced
Year
2020
Paper
Paper 2
Subject
Chemistry
Chapter
Thermodynamics (C)

JEE Advanced 2020 · Paper 2 · Chemistry · Thermodynamics (C)

Tin is obtained from cassiterite by reduction with coke. Use the...

Tin is obtained from cassiterite by reduction with coke. Use the data given below to determine the minimum temperature (in KK) at which the reduction of cassiterite by coke would take place.

298K:ΔfH0(SnO2(s))=−581.0kJmol−1,ΔfH0(CO2(g))=−394.0kJmol−1298K: {\Delta}_{f}{H}^{0}\left({SnO}_{2} ( s )\right) = - 581 . 0kJ{mol}^{- 1}, {\Delta}_{f}{H}^{0}\left({CO}_{2} ( g )\right) = - 394 . 0kJ{mol}^{- 1}

S0(SnO2(s))=56.0JK−1mol−1,S0(Sn(s))=52.0JK−1mol−1{S}^{0}\left({SnO}_{2} ( s )\right) = 56 . 0{JK}^{- 1}{mol}^{- 1}, {S}^{0} ( Sn ( s ) ) = 52 . 0{JK}^{- 1}{mol}^{- 1}

S0(C(s))=6.0JK−1mol−1,S0(CO2(g))=210.0JK−1mol−1{S}^{0} ( C ( s ) ) = 6 . 0{JK}^{- 1}{mol}^{- 1}, {S}^{0}\left({CO}_{2} ( g )\right) = 210 . 0{JK}^{- 1}{mol}^{- 1}

Assume that the enthalpies and the entropies are temperature independent.

Correct answer

935

Step-by-step solution

{\text{SnO}}_{2} ( s ) + \text{C} ( s ) \to \text{Sn} ( s ) + {\text{CO}}_{2} ( g )</p><p></p><p>{\Delta H}_{rxn}^{0} = {\Delta H}_{f}^{0}\left({CO}_{2} ( g )\right) - {\Delta H}_{f}^{0}\left({SnO}_{2} ( s )\right)</p><p></p><p>= - 394 . 0 - [ - 581 . 0 ]</p><p></p><p>= 187KJ</p><p></p><p>{\Delta S}_{rxn}^{0} = {S}^{0} ( Sn ( s ) ) + {S}^{0}\left({CO}_{2} ( g )\right) - {S}^{0}\left({SnO}_{2}, ( s ) - {S}^{0} ( C ( s ) )\right)

=52+210−56−6= 52 + 210 - 56 - 6

=200J= 200J

ΔG∘=ΔH∘−TΔS∘{\Delta G}^{∘} = {\Delta H}^{∘} - {T \Delta S}^{∘}

For reaction to be spontaneous

ΔG∘<0{\Delta G}^{∘} < 0

ΔH∘−TΔS∘<0{\Delta H}^{∘} - {T \Delta S}^{∘} < 0

187×1000−T×200<0187 \times 1000 - T \times 200 < 0

T>935KT > 935K

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