C3

Temporary Hardness - calcium & magnesium ions

• produces a precipitate called limescale when heated
• the dissolved calcium or magnesium compounds that make the water hard, decompose to form insoluble cinoiunds(limescale)
• removing soluble calcium and magnesium ions from the water, means that it will now form a lather with soap easily
• heating softens this type of hard water

Calcium hydrogen carbonate -> calcium carbonate + carbon dioxide + water

Perminant Hardness

• does not lose it's hardness when heated -> still forms a scum with soap
• wastes soap
• hardness sometimes removed before water is used
• heating does not soften
• ion exchange column is needed to softnen this hard water(also works on temporary hard water