Join Date: Apr 2016
Location: Central MA
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I have hard water and bought some 3D Auto Detailing Products Eraser Water Spot Remover 16 Oz - Gel. It helps but isn't instantaneous. I am a chemist and acid in COLD WATER and acid is the way to go for removing inorganic minerals.
The type found deposited on the heating elements of water heaters (scale) consists mainly of calcium carbonate (CaCO3). Hard water contains calcium (and often magnesium) bicarbonate or similar ions. Calcium salts, such as calcium carbonate and calcium bicarbonate (Ca(HCO3)2), are more soluble in hot water than cold water; thus, heating water does not cause calcium carbonate to precipitate per se. However, there is an equilibrium between dissolved calcium bicarbonate and dissolved calcium carbonate as represented by the chemical equation
Ca2+ + 2HCO3− ⇋ Ca2+ + CO32− + CO2 + H2O
where the equilibrium is driven by the carbonate/bicarbonate, not the calcium. Note that the CO2 is dissolved in the water. Carbon dioxide dissolved in water (dis) also tends to equilibrate with carbon dioxide in the gaseous state (g):
CO2(dis) ⇋ CO2(g)
The equilibrium of CO2 also moves to the right towards gaseous CO2 when the water temperature rises. When water that contains dissolved calcium carbonate is warmed, CO2 leaves the water as gas, causing the equilibrium of bicarbonate and carbonate to shift to the right, increasing the concentration of dissolved carbonate. As the concentration of carbonate increases, calcium carbonate precipitates as the salt: Ca2+ + CO32− ⇋ CaCO3.
As new cold water with dissolved calcium carbonate/bicarbonate is added and heated, the process continues: CO2 gas is again removed, carbonate concentration increases, and more calcium carbonate precipitates.