Composite alkalinity

{
  "id": "MLC-T-CHM-002330",
  "term": "Composite alkalinity",
  "field": "Chemistry",
  "definition": "The alkalinity found by titrating with strong acid to the phenolphthalein end point near pH 8.3, which is attributed to all of the hydroxide and half of the carbonate present, as carbonate is converted to bicarbonate. It is zero for solutions at pH 8.3 or below, and it is lower than total alkalinity, which is titrated to about pH 4.5 and also counts bicarbonate.",
  "synonyms": [
    "phenolphthalein end-point alkalinity"
  ],
  "subject": "Analytical Chemistry",
  "see_also": [
    "alkalinity",
    "titrand"
  ],
  "references": [
    "PAC, 2025, 97, 137. 'Glossary of terms for mass and volume in analytical chemistry (IUPAC Recommendations 2024)' on page 2 (https://doi.org/10.1515/pac-2023-0903)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/composite-alkalinity/"
}