Final answer:
The difference between ΔG and ΔG° lies in the measurement conditions. ΔG is for non-standard conditions, while ΔG° is for standard state conditions at 1 bar pressure and a specified temperature.
Step-by-step explanation:
The difference between ΔG (delta G) and ΔG° (delta G naught) concerns the conditions under which the change in Gibbs free energy of a system is measured.
ΔG represents the change in Gibbs free energy for a system under non-standard conditions, which can vary depending on the context (e.g., concentrations, pressures, and temperatures of the reactants and products). ΔG°, on the other hand, is the change in Gibbs free energy measured under standard conditions, which generally specify reactants and products in their standard states at 1 bar of pressure (or 1 atm in some textbooks) and a specified temperature, usually 298.15 K.
The equation used to calculate ΔG° is ΔG° = ΔH° - TΔS°, where T is the absolute temperature in Kelvin and the superscript ° denotes standard state values of enthalpy (ΔH°) and entropy (ΔS°).