The substances that form the basis of our physical world are composed of different types of chemical elements. Four of them are found most often than the rest. These are hydrogen, carbon, nitrogen and oxygen. The last element can bind to particles of metals or nonmetals and form binary compounds - oxides. In our article, we will study the most important methods for producing oxides in laboratory conditions and in industry. Also consider their basic physical and chemical properties.
State of aggregation
Oxides, or oxides, exist in three states: gaseous, liquid, and solid. For example, the first group includes such well-known and widespread in nature compounds as carbon dioxide - CO 2 , carbon monoxide - CO, sulfur dioxide - SO 2 and others. In the liquid phase, there are such oxides as water — H 2 O, sulfuric anhydride — SO 3 , and nitric oxide — N 2 O 3 . The oxides we named can be obtained in the laboratory, but such ones as carbon monoxide and sulfur trioxide are also mined in industry. This is due to the use of these compounds in technological cycles of iron smelting and sulfate acid production. Carbon monoxide is used to reduce iron from ore, and sulfuric anhydride is dissolved in sulfate acid and oleum is mined.
Oxide classification
Several types of oxygen-containing substances consisting of two elements can be distinguished. Chemical properties and methods for producing oxides will depend on which of the listed groups the substance belongs. For example, carbon dioxide related to acid oxides is produced by directly combining carbon with oxygen by conducting a hard oxidation reaction. Carbon dioxide can also be distinguished during the exchange of salts of carbonic acid and strong inorganic acids:
HCl + Na 2 CO 3 = 2NaCl + H 2 O + CO 2
What is the reaction of acid oxides? This is their interaction with alkalis:
SO 2 + 2NaOH → Na 2 SO 3 + H 2 O
Amphoteric and non-salt forming oxides
Indifferent oxides, such as CO or N 2 O, are not capable of reactions leading to the appearance of salts. On the other hand, most acidic oxides can react with water to form acids. However, for silicon oxide this is not possible. It is advisable to obtain silicate acid indirectly: from silicates that react with strong acids. Binary compounds with oxygen that are capable of reactions with both alkalis and acids will be amphoteric. We will include the following compounds in this group - these are the known oxides of aluminum and zinc.
Production of sulfur oxides
In its compounds with oxygen, sulfur exhibits various valencies. So, in sulfur dioxide, the formula of which is SO 2 , it is tetravalent. In the laboratory, sulfur dioxide is obtained in the reaction between sulfate acid and sodium hydrosulfite, the equation of which is
NaHSO 3 + H 2 SO 4 → NaHSO 4 + SO 2 + H 2 O
Another method for extracting SO 2 is the redox process between copper and high concentration sulfate acid. The third laboratory method for producing sulfur oxides is burning a sample of a simple sulfur substance under the hood:
Cu + 2H 2 SO 4 = CuSO 4 + SO 2 + 2H 2 O
In industry, sulfur dioxide can be obtained by burning sulfur-containing minerals of zinc or lead, as well as burning pyrite FeS 2 . Sulfur gas obtained by this method is used to produce sulfur trioxide SO 3 and then sulfate acid. Sulfur dioxide with other substances behaves like oxide with acidic characteristics. For example, its interaction with water leads to the formation of sulfite acid H 2 SO 3 :
SO 2 + H 2 O = H 2 SO 3
This reaction is reversible. The degree of acid dissociation is small, therefore, the compound is classified as weak electrolytes, and sulfuric acid itself can exist only in an aqueous solution. Sulfur anhydride molecules are always present in it, which give the substance a pungent odor. The reacting mixture is in a state of equal concentration of reactants and products, which can be displaced by changing conditions. So, when alkali is added to the solution, the reaction will proceed from left to right. If sulfur dioxide is removed from the reaction sphere by heating or blowing nitrogen gas through a mixture, the dynamic equilibrium will shift to the left.
Sulfuric anhydride
We continue to consider the properties and methods for producing sulfur oxides. If sulfur dioxide is burned, an oxide is formed as a result, in which sulfur has an oxidation state of +6. This is sulfur trioxide. The compound is in the liquid phase, quickly hardens in the form of crystals at temperatures below 16 ° C. The crystalline substance can be represented by several allotropic modifications that differ in the structure of the crystal lattice and melting points. Sulfuric anhydride exhibits the properties of a reducing agent. Interacting with water, it forms an aerosol of sulfate acid, therefore, in the industry, H 2 SO 4 is produced by dissolving sulfuric anhydride in concentrated sulfate acid. The result is an oleum. Adding water to it, and get a solution of sulfuric acid.
Basic oxides
Having studied the properties and production of sulfur oxides belonging to the group of acid binary compounds with oxygen, we consider the oxygen compounds of metal elements.
Basic oxides can be determined by such a feature as the presence in the composition of molecules of metal particles of the main subgroups of the first or second groups of the periodic system. They are alkaline or alkaline earth. For example, sodium oxide - Na 2 O can react with water, resulting in the formation of chemically aggressive hydroxides - alkalis. However, the main chemical property of basic oxides is the interaction with organic or inorganic acids. It comes with the formation of salt and water. If we add hydrochloric acid to the white powdery copper oxide, we will find a bluish-green solution of copper chloride:
CuO + 2HCl = CuCl 2 + H 2 O
The heating of solid insoluble hydroxides is another important way to obtain basic oxides:
Ca (OH) 2 → CaO + H 2 O
Conditions: 520-580 ° C.
In our article, we examined the most important properties of binary compounds with oxygen, as well as methods for producing oxides in the laboratory and industry.