Hard water contains dissolved compounds such as calcium and magnesium salts. There are two types of hard water:
- temporary (hydrogen carbonates)
- permanent (sulfate)
It forms when water flows over rocks containing calcium or magnesium which then dissolves into the water.
- Calcium ions in drinking water help the development of strong bones and teeth.
- Some evidence suggests that hard water helps to reduce heart disease.
The calcium and magnesium ions in hard water can react with soap to form scum:
sodium stearate + Ca2+ ions = calcium stearate precipitate + Na+ ions
(soap) (calcium ions) (scum) (sodium ions, soluble in…