What is gibbs free energy? a) the result of the product of the temperature and entropy of a change, subtracted from the enthalpy of the change. b) the result of the product of the temperature and enthalpy of a change, subtracted from the entropy of the change. c) the result of the product of the temperature and entropy of a change, added to the enthalpy of the change. d) the result of the product of the temperature and enthalpy of a change, added to the entropy of the change.