Question

Gibbs Helmholtz equation relates the enthalpy, entropy and free energy change of the process at constant pressure and temperature as
`DeltaG=DeltaH-TDeltaS " (at constant P, T)"`
In General the magnitude of `DeltaH` does not change much with the change in temperature but the terms `TDeltaS` changes appreciably. Hence in some process spontaneity is very much dependent on temperature and such processes are generally known as entropy driven process.
When `CaCO_(3)` is heated to a high temperature it decomposes into CaO and `CO_(2)`, however it is quite stable at room temperature. It can be explained by the fact that
A. `Delta_(r )H` dominates the term `TDeltaS` at high temperature
B. the term `TDeltaS` dominates the `Delta_(r )H` at high temperature
C. at high temperature both `Delta_(r )S` and `Delta_(r )H` becomes negative
D. thermodynamics can not say anything about spontaneity

Answer 1

Correct Answer - B
`CaCO_(3)rarrCaO+CO_(2)" "DeltaH+ve`
Reaction becomes spontaneous at high temperature because `TDeltaS` dominates over `DeltaH_(rxn)`.