Answer:
43.0 kJ
Step-by-step explanation:
The free energy (ΔG) measures the total energy that is presented in a thermodynamic system that is available to produce useful work, especially at thermal machines. In a reaction, the value of the variation of it indicates if the process is spontaneous or nonspontaneous because the free energy intends to decrease, so, if ΔG < 0, the reaction is spontaneous.
The standard value is measured at 25°C, 298 K, and the value of free energy varies with the temperature. It can be calculated by the standard-free energy of formation (G°f), and will be:
ΔG = ∑n*G°f products - ∑n*G°f reactants, where n is the coefficient of the substance in the balanced reaction.
By the balanced reaction given:
2NOCl(g) --> 2NO(g) + Cl2(g)
At ALEKS Data tab:
G°f, NOCl(g) = 66.1 kJ/mol
G°f, NO(g) = 87.6 kJ/mol
G°f, Cl2(g) = 0 kJ/mol
ΔG = 2*87.6 - 2*66.1
ΔG = 43.0 kJ