Knowra Alkalinity Alkalinity Alkalinity is water’s capacity to neutralize added acid, arising from dissolved bases that accept hydrogen ions. In most natural waters, bicarbonate and carbonate provide most of this capacity.
Carbonate system : The interrelated dissolved forms of carbon dioxide, carbonic acid, bicarbonate, and carbonate in water. Its acid–base reactions supply most alkalinity in natural waters.
pH : A logarithmic measure of hydrogen-ion activity in a solution. pH describes the current acid–base state, not the reserve capacity measured by alkalinity.
Alkalinity titration : An analytical procedure that measures alkalinity by adding a standardized acid to a water sample. It determines how much acid a sample can neutralize.
Basicity : The tendency or capacity of a chemical species to accept protons or donate electron pairs. Basicity describes chemical behavior, while alkalinity measures a solution’s total acid-neutralizing capacity.
Bicarbonate : The hydrogen carbonate ion, HCO₃⁻, a dissolved species that can accept or release a hydrogen ion. It is usually the largest contributor to alkalinity in natural waters.
Acidity : A solution’s capacity to neutralize added base, arising from dissolved acids and acid-forming species. It is the acid-neutralizing counterpart to alkalinity’s base reserve.
Water treatment : Processes that improve water quality for drinking, industrial, or environmental use. Operators monitor alkalinity to manage coagulation, corrosion, and pH stability.
Buffer solution : A solution that resists pH change when limited amounts of acid or base are added. A buffer resists pH change, whereas alkalinity measures acid-neutralizing capacity.
Carbonate ion : The divalent CO₃²⁻ ion, formed when bicarbonate loses a hydrogen ion in water. It neutralizes acid and contributes two equivalents of alkalinity per mole.
Total dissolved solids : The combined mass concentration of dissolved inorganic and organic substances in water. Dissolved ions contribute to water composition, but their total mass does not determine alkalinity.
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