Which of the following thermodynamic relations correctly defines Gibbs free energy change at constant temperature and pressure?

💡 Solution & Explanation

Gibbs free energy change is defined at constant temperature and pressure as the enthalpy change minus the product of absolute temperature and entropy change, expressed as Delta G equals Delta H minus T Delta S. A negative value of Delta G indicates a spontaneous thermodynamic process, while a positive value indicates non-spontaneity. This master equation links the first and second laws of thermodynamics into a single criterion for chemical equilibrium.