Question

For a given reaction, ΔS = +106 J/mol ⋅ K, and the reaction is spontaneous at temperatures above the crossover temperature, 446 K. The value of ΔH = _______ kJ/mol, assuming that ΔH and ΔS do not vary with temperature.

Answer 1

Answer:  47.276 kJ/mol

Explanation:

According to Gibb's equation:

$\Delta G=\Delta H-T\Delta S$

$\Delta G$ = Gibbs free energy  

$\Delta H$ = enthalpy change

$\Delta S$ = entropy change  = +106 J/mol

T = temperature in Kelvin  = 446 K

$\Delta G$= +ve, reaction is non spontaneous

$\Delta G$= -ve, reaction is spontaneous

$\Delta G$= 0, reaction is in equilibrium

$\Delta H=T\Delta S$

$\Delta H=T\Delta S$

$\Delta H=446K\times +106J/Kmol=47276J/mol=47.276kJ/mol$   (1kJ=1000J)

Thus the value of ΔH = 47.276 kJ/mol, assuming that ΔH and ΔS do not vary with temperature.