What does a negative ΔG° indicate about the spontaneous nature of the reaction forming [Cu(NH3)4]2+?

• A. It is a non-spontaneous process
• B. It is a spontaneous process
• C. It demonstrates equilibrium
• D. It signifies a positive entropy change

Answer: (B)

A negative ΔG° indicates that the formation of [Cu(NH3)4]2+ is a spontaneous process under standard conditions. In thermodynamics, the Gibbs free energy change (ΔG°) is a crucial determinant of the spontaneity of a reaction. When ΔG° is less than zero, it means that the reaction can proceed in the forward direction without the need for an external input of energy, suggesting that the products are more thermodynamically favorable than the reactants.

This spontaneity is influenced by both enthalpic and entropic contributions. Although ΔG° does not provide direct information about changes in entropy or enthalpy by itself, it indicates that the combination of these factors, particularly a favorable change in entropy or a strong exothermic reaction, is sufficient to drive the formation of the complex [Cu(NH3)4]2+. Thus, the negative ΔG° confirms that the reaction favors product formation, highlighting its spontaneous nature.