Activity

{
  "id": "MLC-T-CHM-000196",
  "term": "Activity",
  "field": "Chemistry",
  "definition": "A dimensionless quantity that serves as the effective concentration of a species in a real mixture, defined from the chemical potential mu by the relation that a equals the exponential of (mu minus mu0) divided by RT, where mu0 is the chemical potential in the chosen standard state. In an ideal mixture it equals the mole fraction, or the concentration or pressure divided by its standard value. Real solutions deviate, and the ratio of the activity to the ideal value is the activity coefficient.",
  "synonyms": [
    "decay rate",
    "disintegration rate",
    "relative activity"
  ],
  "subject": "Physical and Biophysical Chemistry",
  "see_also": [
    "absolute activity",
    "nuclear decay",
    "chemical potential",
    "gas constant",
    "standard chemical potential",
    "standard state",
    "thermodynamic temperature"
  ],
  "references": [
    "Green Book, 2nd ed., p. 22 (https://goldbook.iupac.org/files/pdf/green_book_2ed.pdf)",
    "PAC, 1994, 66, 2513. 'Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994)' on page 2515 (https://doi.org/10.1351/pac199466122513)",
    "PAC, 1996, 68, 957. 'Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)' on page 960 (https://doi.org/10.1351/pac199668040957)",
    "Green Book, 2nd ed., p. 49 (https://goldbook.iupac.org/files/pdf/green_book_2ed.pdf)",
    "PAC, 1996, 68, 957. 'Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)' on page 989 (https://doi.org/10.1351/pac199668040957)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/activity/"
}