Most metal oxides are basic oxides. It can be said that basic oxides must be metal oxides, but it cannot be said that metal oxides must be basic oxides. Universality of basic oxides: reacting with acids to form salts; And reacts with acid oxides to form salts. Alkali metals and oxides of calcium, strontium and barium can react with water to generate corresponding hydroxides.
1, sodium oxide
Chemical formula Na2O, molecular weight 6 1.979, off-white amorphous flake or powder. Sodium oxide is sensitive to moisture, deliquescent easily, and reacts violently with water to form sodium hydroxide. Physical properties: sodium oxide is off-white amorphous flake or powder at room temperature, with melting point of 1275℃, molecular weight of 6 1.979, density of 2.3g/ cm3, inchi =1s/2na.o/Q2+1; -2, soluble in water.
2. Potassium oxide
The molecular formula is K2O, colorless cubic crystal. The density is 2.32g/cm3, and it decomposes at 350℃, so it is easy to deliquesce, dissolve in water and combine with water to generate potassium hydroxide. Mainly used in inorganic industry, it is the basic raw material for producing various potassium salts such as potassium hydroxide, potassium sulfate, potassium nitrate, potassium chlorate and potassium dichromate. Potassium oxide is a white powder, which dissolves in water to generate potassium hydroxide and gives off a lot of heat. Heating in the air stream can be oxidized into potassium peroxide or potassium peroxide, and it is easy to absorb carbon dioxide in the air into potassium carbonate.
3. Calcium oxide
Calcium oxide is an inorganic compound, its chemical formula is CaO, and its common name is quicklime. Physical properties are white powder on the surface, grayish white if it is impure, pale yellow or gray when it contains impurities, and it has hygroscopicity. Physical properties: white or grayish blocks or particles. Soluble in acids, glycerol and sucrose solutions, almost insoluble in ethanol. The relative density is 3.32 ~ 3.35. Melting point is 2572℃. The boiling point is 2850℃. Refractive index 1.838.