Carbonate hardness
Carbonate hardness, is a measure of the
is equal to 17.848 mg/L (ppm) CaCO3, e.g. one dKH corresponds to the carbonate and bicarbonate ions found in a solution of approximately 17.848 milligrams of calcium carbonate(CaCO
3) per litre of water (17.848 ppm). Both measurements (mg/L or KH) are usually expressed as mg/L CaCO
3 – meaning the concentration of carbonate expressed as if calcium carbonate were the sole source of carbonate ions.
An
Carbonate hardness should not be confused with a similar measure Carbonate Alkalinity which is expressed in either [milli[equivalent]s] per litre (meq/L) or ppm. Carbonate hardness expressed in ppm is exactly equal to carbonate alkalinity expressed in ppm.
whereas
However, for water with a pH below 8.5, the CO32− will be less than 1% of the HCO3− so carbonate alkalinity will equal carbonate hardness to within an error of less than 1%.
In a solution where only CO2 affects the pH, carbonate hardness can be used to calculate the concentration of dissolved CO2 in the solution with the formula CO2 = 3 × KH × 10(7-pH), where KH is degrees of carbonate hardness and CO2 is given in ppm by weight.[citation needed]
The term carbonate hardness is also sometimes used as a synonym for temporary hardness, in which case it refers to that portion of hard water that can be removed by processes such as boiling or lime softening, and then separation of water from the resulting precipitate.[1]
See also
- dGH or DGH or Degree of General Hardness, a measure of the hardness of water
- Hard water
References
- ^ "Lime Softening". Archived from the original on 27 October 2016. Retrieved 4 November 2011.