How is carbon dioxide involved in the formation of hard water?
Ulex writes Rocks containing calcium carbonate such as limestone and some types of sandstone (where the silica grains are held together with calcium carbonate) react with water and atmospheric carbon dioxide to give calcium hydrogencarbonate. This, unlike the calcium carbonate from which it is formed, is soluble in water and its solution contains calcium ions which are responsible for the hardness of water. CaCO3(s) + H2O(l) + CO2(g) -> Ca(HCO3)2 (aq) This equation is reversible so that if the hard water is boiled, carbon dioxide is liberated and calcium carbonate is precipitated the so-called limescale which coats the insides of hot water pipes in hard-water areas. Risk assessment Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school o
