Selectivity coefficient

{
  "id": "MLC-T-CHM-010688",
  "term": "Selectivity coefficient",
  "field": "Chemistry",
  "definition": "An equilibrium coefficient from the mass action law for ion exchange that quantifies how strongly an ion exchanger prefers one ion over another when both are in solution. It carries the two ions as subscripts: for Mg2+ and Ca2+ it is the ratio of their concentrations inside the exchanger divided by the same ratio in the surrounding solution. A value above 1 means the exchanger favours the first-named ion.",
  "synonyms": [
    "selectivity factor"
  ],
  "subject": "Analytical Chemistry",
  "see_also": [
    "coefficient",
    "counter-ions",
    "ion exchange",
    "ion exchanger",
    "amount fraction",
    "selectivity",
    "separation factor"
  ],
  "references": [
    "PAC, 1993, 65, 2373. 'Nomenclature for liquid-liquid distribution (solvent extraction) (IUPAC Recommendations 1993)' on page 2385 (https://doi.org/10.1351/pac199365112373)",
    "PAC, 1993, 65, 819. 'Nomenclature for chromatography (IUPAC Recommendations 1993)' on page 857 (https://doi.org/10.1351/pac199365040819)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/selectivity-coefficient/"
}