Question

The entropy of a system at 337 K increases by 221.7 J/mol•K. The free energy value is found to be –717.5 kJ/mol. Calculate the change in enthalpy of this system. Enter your answer in kJ/mol rounded to the nearest tenths place.

Answer 1

Answer: The change in enthalpy for the given system is -642.8 kJ/mol

Explanation:

To calculate the change in enthalpy for given Gibbs free energy, we use the equation:

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

where,

$\Delta G$ = Gibbs free energy = -717.5 kJ/mol = -717500 J/mol    (Conversion factor: 1 kJ = 1000 J)

$\Delta H$ = change in enthalpy = ?

T = temperature = 337 K

$\Delta S$ = change in entropy = 221.7 J/mol.K

Putting values in above equation, we get:

$-717500J/mol=\Delta H-(337K\times 221.7J/mol.K)\\\\\Delta H=-642787J/mol=-642.8kJ/mol$

Hence, the change in enthalpy for the given system is -642.8 kJ/mol