Almost all the elements of the periodic table can form oxides, or oxides - binary compounds containing oxygen atoms in their molecules. The class of these inorganic compounds, in turn, is divided into several groups: basic, acidic, amphoteric and indifferent oxides. The aim of our article is to study the physical and chemical properties of oxides, as well as their practical application and significance for humans.
Production methods
The main chemical reaction for the production of oxides is the direct interaction of a metal or non-metal with oxygen.
H 2 + O 2 = H 2 O (reaction proceeds with an explosion)
4K + O 2 = 2K 2 O
Other methods for the formation of oxides include the combustion of complex substances, for example, hydrocarbons. It ends with the production of carbon dioxide and water. Thermal decomposition of water-insoluble bases or salts: carbonates, nitrates also releases oxides. Examples of such reactions are given below:
- Fe (OH) 2 = FeO + H2O iron (II) oxide
- 2KNO 3 = 2KNO 2 + O 2 ↑
Physical characteristic
The aggregate state of binary oxygen compounds with metals or non-metals can be different. For example, carbon oxides, nitrogen dioxide, sulfur dioxide (IV) - gases. Liquids are water, sulfuric anhydride, and metal oxides are solids. The solubility of the compounds is also different. Let us give examples of oxides with varying degrees of interaction with water. So, carbon dioxide dissolves in water at room temperature in a ratio of 1: 1, nitric oxide (II) is sparingly soluble, and silicon dioxide is completely insoluble.
Basic oxides
If atoms of typical metals are included in a molecule of a substance, it exhibits basic properties. The substance will react with acids and acid oxides, as well as with water. For example, calcium oxide can react with perchloric acid:
2HCl + CaO = CaCl 2 + H 2 O.
The reaction products are medium salt and water. If the same calcium oxide interacts with carbon monoxide, then we get one substance - salt.
CaO + CO 2 = CaCO 3 .
The properties of oxides formed by metals have found application in various industries. Thus, calcium oxide, also called quicklime or burnt lime, is important as a raw material for the production of slaked lime. Calcium hydroxide is widely used in industry as a mortar. Lime water is used as an indicator of the presence of carbon dioxide molecules in a solution.
Examples of oxides that make up iron ore are FeO and Fe 2 O 3 — brown and magnetic iron ore. In the blast furnace they are reduced with coke and carbon oxides and get an alloy of iron with carbon - cast iron. In the course of its further processing in the metallurgical industry smelted various grades of steel, including alloy steel.
The reaction of alkali or alkaline earth metal oxides with water leads to alkali.
Characterization of Acid Oxides
The oxides of nitrogen, carbon, sulfur, silicon, etc. form a group of acid oxides. The chemical properties of oxides are reactions with alkalis, basic oxides and water. The products of the interaction between potassium hydroxide and carbon dioxide are potassium carbonate and water. If the sodium base and silicon dioxide react with each other, we get sodium silicate and water.
Some acid oxides react with water. The reaction product is the corresponding acid (carbonic):
CO 2 + H 2 O = H 2 CO 3 .
Acid oxides, examples of which we will give below, are important. So, sulfuric anhydride SO 3 - a colorless liquid, is the feedstock for the industrial production of sulfate acid - the main product of the chemical industry. Nitrogen compounds, for example NO 2 , are used to produce nitrate acid. In addition to nitrogen dioxide, water and oxygen are also involved in the reaction. Nitric acid obtained by the reaction of nitrogen oxides with water is used in the production of mineral fertilizers, explosives, dyes, pharmaceuticals, plastics, etc.
Amphoteric compounds
Oxides, which include, for example, zinc or aluminum atoms, exhibit dual chemical properties. They can react with both acids and alkalis. In this case, the reaction products are medium salts. Here is a description of the physical properties of some amphoteric oxides, examples of which we will consider. So, Al 2 O 3 is corundum, it is a solid substance, the melting point of which reaches 2050 °. In nature, oxide is part of alumina, and also forms colored crystals, which are precious stones - rubies and sapphires.
Zinc oxide ZnO are colorless crystals, at a temperature of 1800 ° C, turning into a state of vapor. This phenomenon is called sublimation. The substance is insoluble in water; when inhaled, dust particles cause poisoning. Zinc oxide has found application as an abrasive material, in the manufacture of paints, artificial leather, in medicine, and in dentistry - as a filling material.
In our article, we studied the classification of oxides, their chemical and physical properties, as well as industrial applications.