Reference state

{
  "id": "MLC-T-CHM-010083",
  "term": "Reference state",
  "field": "Chemistry",
  "definition": "A specific state of a substance, defined by a set of conditions, used as a baseline for comparing its thermodynamic properties. It establishes a zero point for properties like enthalpy, entropy, and Gibbs free energy. For an element, the reference state is its most stable allotropic form at a standard pressure of 1 bar and a specified temperature, for which the standard enthalpy of formation is defined as zero.",
  "subject": "Physical and Biophysical Chemistry",
  "see_also": [
    "stable"
  ],
  "references": [
    "PAC, 1982, 54, 1239. 'Notation for states and processes, significance of the word standard in chemical thermodynamics, and remarks on commonly tabulated forms of thermodynamic functions' on page 1249 (https://doi.org/10.1351/pac198254061239)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/reference-state/"
}