Calcium ... What do you know about it? "This is metal," - many will answer. And what calcium compounds exist? With this question everyone will begin to scratch in the back of the head. Yes, there are few knowledge about the latter, and about calcium itself, too. Okay, we'll talk about it later, and today let's analyze at least three of its compounds - carbonate, hydroxide and calcium bicarbonate.
1. Calcium carbonate
It has the appearance of a white powder, insoluble in water and ethyl alcohol.
Preparation of calcium carbonate
It is formed by calcination of calcium oxide. Water is added to the latter, and then carbon dioxide is carried through the resulting solution of calcium hydroxide . The reaction products are the desired carbonate and water, which are easily separated from each other. If it is heated, there will be a splitting, the products of which will be carbon dioxide and quicklime. By dissolving this carbonate and carbon monoxide (II) in water, calcium hydrogen carbonate can be obtained. If you combine carbon and calcium carbonate, the products of this reaction are calcium carbide and carbon monoxide.
This carbonate is chalk, which we regularly meet in schools and other primary and higher educational institutions. Also, they bleached ceilings, paint in the trunks of trees in the spring and alkalize the soil in the horticulture industry.
2. Calcium bicarbonate
It dissolves in water, like all hydrocarbonates. However, for a while it makes it tough. In living organisms calcium bicarbonate and some other salts with the same residue have the function of regulators of constancy of reactions in the blood.
It is obtained by the interaction of carbon dioxide, calcium carbonate and water.
It is contained in drinking water, where its concentration can be different - from 30 to 400 mg / l.
3. Calcium hydroxide
It forms when calcium oxide and water interact.
It has the appearance of a white powder, slightly soluble in water. With increasing temperature, the numerical value of solubility decreases. Also has the ability to neutralize acids, this reaction produces the corresponding calcium salts and water. If carbon dioxide dissolved in water is added to it, the same water will be obtained, as well as calcium carbonate. When CO2 bubbling continues, calcium hydrogencarbonate will form.
They are whitewashed rooms, wooden fences, as well as plastered rafters. With the help of this hydroxide, a calcareous mortar, chlorine lime, special fertilizers and silicate concrete are prepared, and the carbonate hardness of the water is also eliminated (soften the latter). By means of this substance, causticization of potassium and sodium carbonates is carried out, the root canals of the teeth are disinfected, the skin is dyed and some plant diseases are cured. Calcium hydroxide is also known as food additive E526.
Now do you understand why in this article I decided to describe these three substances? After all, these compounds "meet" each other during the decomposition and receipt of each of them. There are many other related substances, but we'll talk about them some other time.