Degrees of carbonate hardness (dKH or °KH; the K is from the German ''Karbonathärte'') is a

unit Unit may refer to: Arts and entertainment * UNIT, a fictional military organization in the science fiction television series ''Doctor Who'' * Unit of action, a discrete piece of action (or beat) in a theatrical presentation Music * ''Unit'' (alb ...

water hardness Hard water is water that has high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of limestone, chalk or gypsum, which are largely made up of calcium and magnesium carbonates, bicarbo ...

, specifically for temporary or

carbonate hardness Carbonate hardness, is a measure of the water hardness caused by the presence of carbonate () and bicarbonate () anions. Carbonate hardness is usually expressed either in degrees KH (dKH) (from the German ''"Karbonathärte"''), or in ''parts per mi ...

. Carbonate hardness is a measure of the concentration of carbonates such as calcium carbonate (CaCO₃) and

magnesium carbonate Magnesium carbonate, (archaic name magnesia alba), is an inorganic salt that is a colourless or white solid. Several hydrated and basic forms of magnesium carbonate also exist as minerals. Forms The most common magnesium carbonate forms are ...

(MgCO₃) per volume of water. Specifically, 1 dKH is defined as 17.86 milligrams (mg) of calcium carbonate per litre of water, i.e. 17.86 ppm. Since a mole of calcium carbonate weighs 100.09 grams, 1 dKH is equivalent to 0.17832

mmol The mole, symbol mol, is the unit of amount of substance in the International System of Units (SI). The quantity amount of substance is a measure of how many elementary entities of a given substance are in an object or sample. The mole is define ...

per litre. dKH are the same as °fH, degrees of French hardness.

External links

Water Hardness definitionsConvertor for Hardness of waterWhat is Temporary Hardness
Water chemistry Units of chemical measurement {{water-stub

See also

External links