1. Tardigrade
  2. Question
  3. Chemistry
  4. Tin is obtained from cassiterite by reduction with coke. Use the data given below to determine the minimum temperature (in K ) at which the reduction of cassiterite by coke would take place. At 298 K ; Δf H0( SnO 2(s))=-581.0 kJ mol -1, Δf H0( CO 2(g))=-394.0 kJ mol -1, S0( SnO 2(s))=56.0 J K -1 mol -1, S0( Sn (s))=52.0 J K -1 mol -1, S0( C (s))=6.0 J K -1 mol -1, S0( CO 2(g))=210.0 J K -1 mol -1, Assume that the enthalpies and the entropies are temperature independent.

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Q. Tin is obtained from cassiterite by reduction with coke. Use the data given below to determine the minimum temperature (in $K$ ) at which the reduction of cassiterite by coke would take place.
At $298 \,K ; \Delta_f H^{0}\left( SnO _{2}(s)\right)=-581.0 \,kJ\, mol ^{-1}, \Delta_{f} H^{0}\left( CO _{2}(g)\right)=-394.0\, kJ \,mol ^{-1}$,
$S^{0}\left( SnO _{2}(s)\right)=56.0 \,J \,K ^{-1} mol ^{-1}, S^{0}( Sn (s))=52.0 \,J \,K ^{-1} mol ^{-1}$,
$S^{0}( C (s))=6.0\, J\, K ^{-1} mol ^{-1}, S^{0}\left( CO _{2}(g)\right)=210.0 \,J \,K ^{-1} mol ^{-1}$,
Assume that the enthalpies and the entropies are temperature independent.

JEE AdvancedJEE Advanced 2020

Solution:

$SnO _{2}( s )+ C ( s ) \longrightarrow Sn ( s )+ CO _{2}( g )$
$\Delta H _{ r }^{0}=-394.0+581=187 \,kJ\,mol ^{-1}$
$\Delta S^{0}=210+52-6-56=200 \,J\,mol ^{-1} K ^{-1}$
Equilibrium temperature $( T )_{\text {eq }}=\frac{187 \times 1000}{200}=935 \,K$
So, $T >935\, K$ (for spontaneity)