Calcium ... What do you know about it? “This is metal,” many will answer. What calcium compounds exist? With this question, everyone will start scratching in the back of the head. Yes, a little knowledge about the latter, and about calcium itself, too. Okay, we'll talk about him later, and today let's analyze at least three of its compounds - calcium carbonate, hydroxide and calcium hydrogen carbonate.
1. Calcium carbonate
It is the salt that calcium and the residue of carbonic acid form. The formula for this carbonate is CaCO
3 .
The properties
It has the appearance of a white powder, insoluble in water and ethyl alcohol.
Obtaining calcium carbonate
It is formed during calcination of calcium oxide. Water is added to the latter, and then carbon dioxide is passed through the resulting calcium hydroxide solution. The reaction products are the desired carbonate and water, which are easily separated from each other. If it is heated, then splitting will occur, 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 carbon and calcium carbonate are combined, the products of this reaction will be calcium carbide and carbon monoxide.
Application
This carbonate is a chalk that we regularly meet in schools and other elementary and higher educational institutions. They also have whitewashed ceilings, paint tree trunks in spring, and alkalize the soil in the horticulture industry.
2. Calcium bicarbonate
It is a
salt of carbonic acid. It has the formula Ca (HCO
3 )
2 .
The properties
It is soluble in water, like all bicarbonates. However, he makes her stiff for a while. In living organisms, calcium bicarbonate and some other salts with the same residue have the function of regulators of the constancy of reactions in the blood.
Getting
It is obtained by the interaction of carbon dioxide, calcium carbonate and water.
Application
It is found in drinking water, where its concentration may be different - from 30 to 400 mg / l.
3. Calcium hydroxide
The formula is Ca (OH)
2 . This substance is a strong base. In various sources it can be called
slaked lime or "fluff".
Getting
Formed when calcium oxide and water interact.
The properties
It has the appearance of a white powder, slightly soluble in water. With increasing temperature of the latter, the numerical value of solubility decreases. It also has the ability to neutralize acids; in this reaction, the corresponding calcium salts and water are formed. If you add carbon dioxide dissolved in water to it, you get the same water, as well as calcium carbonate. With continued bubbling of CO 2 , calcium bicarbonate will form.
Application
They are whitewashed rooms, wooden fences, as well as coated with rafters. Using this hydroxide, lime mortar, bleach, special fertilizers and silicate concrete are prepared, and they also eliminate the carbonate hardness of the water (soften the latter). Using this substance, caustification of potassium and sodium carbonates is carried out, the root canals of the teeth are disinfected, the skin is tanned and some plant diseases are cured. Calcium hydroxide is also known as the food supplement E526.
Conclusion
Now you understand why in this article I decided to describe these three substances? After all, these compounds "meet" with each other during the decomposition and receipt of each of them. There are many other related substances, but we'll talk about them another time.