Final answer:
When a reaction has negative enthalpy and negative entropy, the value of Gibbs Free Energy will determine whether the reaction is spontaneous or not. If the reaction has negative AG, it will be spontaneous. If the reaction has positive AG, it will not be spontaneous. An exception is when the reaction is at equilibrium.
Step-by-step explanation:
When a reaction has a negative enthalpy (AH < 0) and a negative entropy (AS < 0), the value of Gibbs Free Energy (AG) will determine whether the reaction is spontaneous or not. If the reaction has a negative value of AG (AG < 0), the reaction will be spontaneous at all temperatures. This means that the reaction will occur on its own without the need for any external influence.
However, if the reaction has a positive value of AG (AG > 0), the reaction will not be spontaneous and will require an external influence to occur. This means that the reaction will not occur on its own and will need to be driven by adding energy or changing the conditions.
An exception to this rule is when the reaction is at equilibrium. In an equilibrium process, the value of AG is zero (AG = 0), indicating that there is no free energy change and the reaction is in a state of balance.