Calcium oxide. Physical, thermal and chemical properties. Application.

Calcium oxide is a crystalline compound of white color. Other names of this substance are quicklime, calcium oxide, "kirabit", "kipelka". Calcium oxide, the formula of which CaO, and its product of interaction with (H2O) water - Ca (OH) 2 ("pushers", or hydrated lime) have found wide application in the construction industry.

How is calcium oxide obtained?

1. The industrial method of obtaining this substance consists in the thermal (under the influence of temperature) decomposition of limestone (calcium carbonate) :

CaCO3 (limestone) = CaO (calcium oxide) + CO2 (carbon dioxide)

2. Also calcium oxide can be obtained by the interaction of simple substances:

2Ca (calcium) + O2 (oxygen) = 2CaO (calcium oxide)

3. The third method of obtaining calcium oxide is the thermal decomposition of calcium hydroxide (Ca (OH) 2) and calcium salts of several oxygen-containing acids:

2Ca (NO3) 2 (calcium nitrate) = 2CaO (resulting material) + 4NO2 (nitric oxide) + O2 (oxygen)

Physical properties of calcium oxide

1. Appearance: a crystalline compound of white color. Crystallized by the type of sodium chloride (NaCl) in a cubic crystal face-centered lattice.

2. The molar mass is 55.07 g / mol.

3. The density is 3.3 grams / centimeter³.

The thermal properties of calcium oxide

1. The melting point is 2570 degrees

2. The boiling point is 2850 degrees

3. The molar heat capacity (under standard conditions) is 42.06 J / (mol · K)

4. The enthalpy of formation (under standard conditions) is -635 kJ / mol

Chemical properties of calcium oxide

Calcium oxide (formula CaO) is the basic oxide. Therefore, he can:

- dissolve in water (H2O) with release of energy. In this case, calcium hydroxide is formed. This reaction looks like this:

CaO (calcium oxide) + H2O (water) = Ca (OH) 2 (calcium hydroxide) + 63.7 kJ / mol;

- react with acids and acid oxides. In this case, salts are formed. Here are examples of reactions:

CaO (calcium oxide) + SO2 (sulfurous anhydride) = CaSO3 (calcium sulphite)

CaO (calcium oxide) + 2HCl (hydrochloric acid) = CaCl2 (calcium chloride) + H2O (water).

Application of calcium oxide:

1. The main volumes of the substance we are considering are used in the production of silicate bricks in construction. Previously, quicklime was used as lime cement. It was obtained by mixing it with water (H2O). As a result, calcium oxide was converted to hydroxide, which then, after absorbing carbon dioxide (CO2) from the atmosphere, hardened, turning into calcium carbonate (CaCO3). Despite the cheapness of this method, at present cement lime is practically not used in construction, since it has the ability to absorb and accumulate liquid in itself.

2. As a refractory material, calcium oxide is suitable as an inexpensive and affordable material. Fused calcium oxide has a resistance to water (H2O), which allowed it to be used as a refractory where the use of expensive materials is impractical.

3. The laboratories use a higher calcium oxide to dry out those substances that do not react with it.

4. In the food industry, this substance is registered as a food additive under the designation E 529. Used as an emulsifier to create a homogeneous mixture of immiscible substances - water, oil and fat.

5. In industry, calcium oxide is used to remove sulfurous anhydride (SO2) from flue gases. Apply, as a rule, 15% water solution. As a result of the reaction in which slaked lime and sulfur dioxide react, gypsum CaCO4 and CaCO3 are obtained. During the experiments, scientists achieved a rate of 98% of smoke cleaning from sulfur dioxide.

6. Used in special "self-heating" dishes. A container with a small amount of calcium oxide is located between the two walls of the vessel. When the capsule is pierced in water, a reaction begins with the release of a certain amount of heat.