TYPES OF HARDNESS

Created Feb. 7, 2024 by G DEEPA

HARDNESS is divided into two types.They are:

*TEMPORARY HARDNESS

*PERMANENT HARDNESS

TEMPORARY HARDNESS

Temporary hardness is a type of water hardness caused by the presence of dissolved bicarbonate minerals (calcium bicarbonate and magnesium bicarbonate). When dissolved, these minerals yield calcium and magnesium cations (Ca2+, Mg2+) and carbonate and bicarbonate anions (CO32−, HCO3−). The presence of the metal cations makes the water hard. However, unlike the permanent hardness caused by sulfate and chloride compounds, this "temporary" hardness can be reduced either by boiling the water, or by the addition of lime (calcium hydroxide) through the process of lime softening.[3] Boiling promotes the formation of carbonate from the bicarbonate and precipitates calcium carbonate out of solution, leaving water that is softer upon cooling.

PERMANENT HARDNESS:

Permanent hardness (mineral content) are generally difficult to remove by boiling.[4] If this occurs, it is usually caused by the presence of calcium sulfate/calcium chloride and/or magnesium sulfate/magnesium chloride in the water, which do not precipitate out as the temperature increases. Ions causing permanent hardness of water can be removed using a water softener, or ion exchange column.

Permanent Hardness = Permanent Calcium Hardness + Permanent Magnesium Hardness.

Return to top