Final answer:
The correct equation for Gibbs free energy is ΔG = ΔH - TΔS, allowing prediction of the spontaneity of chemical processes at constant temperature and pressure.
Step-by-step explanation:
The important equations in thermodynamics regarding Gibbs free energy are centered on the function G, named in honor of the American scientist Josiah Gibbs. The change in Gibbs free energy is denoted as ΔG, which is the difference between the change in enthalpy (ΔH) and the product of the temperature in Kelvin (T) and the change in entropy (ΔS) of the system. Thus, the correct equation is:
ΔG = ΔH - TΔS
This equation is fundamental because it allows chemists to predict the spontaneity of a process without the need to measure the entropy change of the surroundings. Spontaneous processes are characterized by a negative ΔG at constant temperature and pressure, indicating an overall increase in entropy of the universe.