2007-10-28 10:49:26 · 4 answers · asked by JitterBug589 3 in Science & Mathematics ➔ Chemistry
It depends on whether the water is temporarily or permanently hard.
In temporarily hard water the culprit is calcium bicarbonate
CaHCO3. On boiling this breaks down to calcium carbonate (which precipitates out as fur in your kettle) and carbon dioxide.
Permanently hard water is usually so because of the presence of calcium sulphate CaSO4 which, like calcium bicarbonate is sparingly soluble in water but more so than calcium carbonate.
2007-10-28 10:59:45 · answer #1 · answered by Anonymous · 0⤊ 1⤋
Calcium carbonate (CaCO3) is a common source of Calcium in "permanently hard" water... it is found in the minerals limestone, chalk, and aragonite.
Calcium bicarbonate (Ca(HCO3)2) is a mineral similar to baking soda which is found in water that is "temporarily hard". If you boil that water, it decomposes into the gas carbon dioxide and also calcium carbonate (CaCO3). The calcium carbonate settles out of the water and becomes "hard water" deposits in a shower/bathtub, coffee maker or teakettle.
Calcium sulfate (CaSO4) is found in the mineral anhydrite, & in the mineral gypsum Gypsum (CaSO4-2H2O). It is somewhat soluble in water and is also a mineral supplying calcium, found in hard water.
Dolomite (CaMg(CO3)2) is also found in hard water, and supplies both Calcium and Magnesium.
2007-10-28 11:18:54 · answer #2 · answered by Anonymous · 0⤊ 0⤋
calcium, lime stone, marble...
2007-10-28 10:53:55 · answer #3 · answered by Anonymous · 0⤊ 1⤋
lime stone, marble
2007-10-28 10:52:45 · answer #4 · answered by steve_geo1 7 · 0⤊ 1⤋