Final answer:
The correct formula for delta G is ΔG = ΔH - TΔS, which calculates the change in free energy for a chemical reaction and determines the spontaneity of the process.
Step-by-step explanation:
The formula for calculating the change in free energy (delta G) in a chemical reaction is ΔG = ΔH - TΔS, where ΔH represents the change in enthalpy, T is the absolute temperature in Kelvin, and ΔS is the change in entropy. Correctly, the formula is none of the options provided by the student. Instead, it is derived by subtracting the product of temperature (T) and entropy change (ΔS) from the enthalpy change (ΔH) of the system.
An exergonic reaction, where ΔG is negative, releases free energy and occurs spontaneously in the forward direction. Conversely, an endergonic reaction, with a positive ΔG, requires an input of energy and is non-spontaneous unless driven by external forces.