Thermodynamics

Thermodynamics

Question

In the conversion of limestone to lime, CaCO3(s) → CaO(s) + CO2(g) the values of ∆Hº and ∆Sº are + 179.1 kJ mol–1 and 160.2 J/K respectively at 298K and 1 bar. Assuming that ∆Hº and ∆Sº do not change with temperature, temperature above which conversion of limestone to lime will be spontaneous is

  • 1008 K

  • 1200 K

  • 845 K

  • 1118 K

Answer

D.

1118 K

We know, ∆G = ∆H-T∆S
So, lets find the equilibrium temperature, i.e. at which
∆G = 0
∆H-T∆S
T= 179.1 x 1000/160.2
= 1118 K
So, at the temperature above this, the reaction becomes will spontaneous.

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