Binary compounds of oxygen with non-metallic elements are a large group of substances that are included in the class of oxides. Many non-metal oxides are well known to everyone. These are, for example, carbon dioxide, water, nitrogen dioxide. In our article, we will consider their properties, find out the scope of binary compounds and their impact on the environment.
General characteristics
Almost all non-metallic elements, with the exception of fluorine, argon, neon and helium, can form oxides. Most elements have multiple oxides. For example, sulfur forms two compounds: sulfur dioxide and sulfuric anhydride. These are substances in which the valency of sulfur is four and six, respectively. Hydrogen and boron have only one oxide each, and nitrogen has the largest number of binary substances with oxygen. Higher oxides are those in which the oxidation state of the non-metal atom is equal to the number of the group where the element is located in the periodic system. So, CO2 and SO3 are higher oxides of carbon and sulfur. Some connectionsmay undergo further oxidation. For example, carbon monoxide in this case turns into carbon dioxide.
Structure and physical properties
Practically all known non-metal oxides consist of molecules, between the atoms of which covalent bonds are formed. The particles of a substance themselves can be either polar (for example, in sulfur dioxide) or non-polar (carbon dioxide molecules). Silicon dioxide, which is a natural form of sand, has an atomic structure. The state of aggregation of a number of acidic oxides can be different. So, carbon oxides, such as carbon monoxide and carbon dioxide, are gaseous, and binary oxygen compounds of hydrogen (H2O) or sulfur are in the highest oxidation state (SO3) are liquids. A feature of water is that the oxide is non-s alt-forming. They are also called indifferent.
Sulfur trioxide or sulfuric anhydride is a crystalline white substance. It quickly absorbs moisture from the air, so sulfur dioxide is stored in sealed glass flasks. The substance is used as an air dryer and in the production of sulfate acid. Oxides of phosphorus or silicon are solid crystalline substances. The mutual transformation of the state of aggregation is characteristic of nitrogen oxides. So, the compound NO2 is a brown gas, and the compound with the formula N2O4 has a colorless liquid or white solid. When heated, the liquid turns into a gas, and when it is cooled,the formation of a liquid phase.
Interaction with water
Reactions of acid oxides with water are known. The reaction products will be the corresponding acids:
SO3 + H2O=H2SO 4 – sulfate acid
These include the interaction of phosphorus pentoxide, as well as sulfur dioxide, nitrogen, carbon with H2O molecules. However, silicon oxide does not react directly with water. To obtain silicate acid, an indirect method is used. First, SiO2 is fused with an alkali such as sodium hydroxide. The resulting middle s alt, sodium silicate, is treated with a strong acid, such as chloride.
The result is a white gelatinous precipitate of silicic acid. Silicon dioxide can react with s alts when heated to form volatile acidic oxides. Acid oxides include several compounds of nitrogen, sulfur and phosphorus, which are the leading contributors to air pollution. They interact with atmospheric moisture, which leads to the formation of sulfuric, nitrate and nitrous acid. Their molecules, along with rain or snow, fall on plants and soil. Acid precipitation not only harms crops by reducing their yields, but also negatively affects human he alth. They destroy buildings made of limestone or marble, cause corrosion of metal structures.
Indifferent oxides
Acid oxides include a group of compounds that cannot react with either acids or alkalis and do not forms alt. All of the above compounds do not correspond to either acids or bases, that is, they are non-s alt-forming. There are few such connections. For example, these include carbon monoxide, nitrous oxide and its monoxide - NO. He, along with nitrogen dioxide and sulfur dioxide, is involved in the formation of smog over large industrial enterprises and cities. The formation of toxic oxides can be prevented by lowering the combustion temperature of the fuel.
Interaction with alkalis
The ability to react with alkalis is an important feature of acidic oxides. For example, when sodium hydroxide and sulfur trioxide react, a s alt (sodium sulfate) and water are formed:
SO3 + 2NaOH → Na2SO4 + H 2O
Nitrogen dioxide belongs to acidic oxides. Its interesting feature is the reaction with alkali, two types of s alts are found in the products: nitrates and nitrites. This is due to the ability of nitric oxide (IV) when interacting with water to form two acids - nitric and nitrous. Sulfur dioxide also interacts with alkalis, thus forming medium s alts - sulfites, as well as water. The compound, getting into the air, strongly pollutes it, therefore, at enterprises using fuel with an admixture of SO2, exhaust industrial gases are cleaned by spraying quicklime or chalk into them. You can also pass sulfur dioxide through lime water or sodium sulfite solution.
The role of binary oxygen compounds of non-metallic elements
Many acid oxidesare of great practical importance. For example, carbon dioxide is used in fire extinguishers because it does not support combustion. Silicon oxide - sand, is widely used in the construction industry. Carbon monoxide is the feedstock for the production of methyl alcohol. Phosphorus pentoxide is an acidic oxide. This substance is used in the production of phosphoric acid.
Binary oxygen compounds of non-metals affect the human body. Most of them are toxic. We talked about the harmful effects of carbon monoxide earlier. The negative impact of nitrogen oxides, especially nitrogen dioxide, on the respiratory and cardiovascular systems has also been proven. Acid oxides include carbon dioxide, which is not considered a toxic substance. But if its volume fraction in the air exceeds 0.25%, a person develops symptoms of suffocation, which can be fatal due to respiratory arrest.
In our article, we studied the properties of acid oxides and gave examples of their practical significance in human life.
