What is the standard condition of free energy of formation for elements in their natural state?

The standard condition of free energy of formation for elements in their natural state is defined as zero. This means that when considering the formation of a compound from its constituent elements, if those elements are in their standard state (which is typically their most stable form at 1 bar of pressure and a specific temperature, usually 25°C), their standard free energy of formation is set to zero. This convention simplifies the calculation of free energies for reactions involving elements and compounds since it serves as a reference point.

By using this standard, any calculated change in free energy during a chemical reaction can be directly attributed to the compounds being formed or consumed, allowing for clearer assessments of thermodynamic favorability and stability.