Water Hardness

Scum

Ca2+ or Mg2+ react with sodium stearate in soap to form calcium stearate (or Mg stearate)...scum

EDTA

Ethylenediaminetetraacetic acid...a metal chelator

Carbonic Acid

Formed when carbon dioxide dissolves in water...rainwater

Temporary Hardness

Hardness in water that can be removed by boiling

Permanent Hardness

Hardness in water that can only be removed by methods other than boiling (e.g., ion exchange or distillation)

Deionised Water

Is water that has been passed through an ion exchanger and the positive and negative ions removed. It may contain dissolved covalent solids or bacteria.

Limescale

The insoluble substance formed when temporary hard water is boiled, it is called calcium carbonate

Distilled Water

This is water that has been evaporated and re-condensed in an enclosed container so that any dissolved solids are removed from the water. It is very pure.

Hard Water

Water that will not easily form a lather with soap

Permanent Hardness

caused by Calcium or Magnesium Chlorides or Sulfates

Temporary Hardness

caused by Calcium or Magnesium Hydrogencarbonate

Water Hardness

caused by the presence of Ca2+ or Mg2+ ions