Removing hardness
Removing hardness You have now seen how hard water is formed. The calcium or magnesium in the water is present as charged particles called ions. The most common cause of hardness is the calcium ion, Ca + (aq). These calcium ions react with ions from soap (sodium stearate) to form scum calcium ions (aq) + stearate ions (aq) hard water calcium stearate (s) soap scum If we can remove these Ca* ions from the water we will get rid of the hardness. Temporary hardness Do you remember how calcium ions from insoluble calcium carbonate get into hard water? Limestone reacts with acidic rainwater. It forms a solution of calcium ions and hydrogencarbonate ions. This is called temporary hardness. When this solution is boiled, the calcium and hydrogencarbonate ions react. They turn back into the insoluble calcium carbonate. Therefore calcium ions are removed from the water. c...