Sulfur Oxide

Sulfur is common in the earth's crust, among the other elements it occupies the sixteenth place. It occurs both in a free state and in a connected form. Non-metallic properties are characteristic for this chemical element. Its Latin name is "Sulfur", denoted by the symbol S. The element is a part of various ions of compounds containing oxygen and / or hydrogen, forms many substances belonging to classes of acids, salts and several oxides, each of which can be called sulfur oxide with addition Symbols denoting valence. The degree of oxidation that it exhibits in various compounds is +6, +4, +2, 0, -1, -2. Oxides of sulfur with different degrees of oxidation are known. The most common are sulfur dioxide and trioxide. Less well-known are sulfur monoxide, as well as higher (except SO3) and lower oxides of this element.

Sulfur monoxide

An inorganic compound called sulfur oxide II, SO, in appearance this substance is a colorless gas. Upon contact with water, it does not dissolve, but reacts with it. This is a very rare compound that occurs only in a rarefied gas environment. The SO molecule is thermodynamically unstable, initially converted to S2O2, (called disulfur gas or sulfur peroxide). Due to the rare occurrence of sulfur monoxide in our atmosphere and the low stability of the molecule, it is difficult to fully determine the hazards of this substance. But in condensed or more concentrated form, the oxide is converted to peroxide, which is relatively toxic and corrosive. This compound is also easily ignited (methane resembles this property), sulfur dioxide dioxide - a toxic gas - is produced during combustion. Sulfur dioxide 2 was discovered near Io (one of the satellites of Jupiter), in the atmosphere of Venus and in the interstellar medium. It is assumed that on Io it is obtained as a result of volcanic and photochemical processes. The main photochemical reactions are as follows: O + S2 → S + SO and SO2 → SO + O.

Sulphur dioxide

Sulfur dioxide IV, or sulfur dioxide (SO2) is a colorless gas with an asphyxiating, pungent odor. At a temperature of minus 10 C, it turns into a liquid state, and at a temperature of minus 73 C hardens. At 20 ° C, about 40 volumes of SO2 are dissolved in 1 liter of water.

This sulfur oxide, dissolving in water, forms sulfurous acid, since it is its anhydride: SO2 + H2O ↔ H2SO3.

It interacts with bases and basic oxides: 2NaOH + SO2 → Na2SO3 + H2O and SO2 + CaO → CaSO3.

For sulfur dioxide, the properties of both the oxidizing agent and the reducing agent are characteristic. It is oxidized by air oxygen to sulfuric anhydride in the presence of a catalyst: SO2 + O2 → 2SO3. With strong reducing agents, such as hydrogen sulphide, it plays the role of oxidizer: H2S + SO2 → S + H2O.

Sulphurous gas in industry is used mainly for the production of sulfuric acid. Sulfur dioxide is obtained by burning sulfur or iron pyrites: 11O2 + 4FeS2 → 2Fe2O3 + 8SO2.

Sulfuric anhydride

Sulfur oxide VI, or sulfur trioxide (SO3) is an intermediate product and has no independent value. In appearance it is a colorless liquid. It boils at a temperature of 45 ° C, and below 17 ° C turns into a white crystalline mass. This higher sulfur oxide (with a degree of oxidation of the sulfur atom + 6) is extremely hygroscopic. With water, it forms a sulfuric acid: SO3 + H2O ↔ H2SO4. Dissolving in water, gives off a lot of heat and, if you add not gradually, but immediately a large amount of oxide, then an explosion may occur. Sulfur trioxide is readily soluble in concentrated sulfuric acid with the formation of oleum. The content of SO3 in oleum reaches 60%. For this sulfur compound, all the properties of the acid oxide are characteristic .

Higher and lower sulfur oxides

Higher sulfur oxides are a group of chemical compounds with the formula SO3 + x, where x can be 0 or 1. The monomeric oxide SO4 contains peroxo group (OO) and is characterized, like SO3 oxide, by the oxidation degree of sulfur +6. This sulfur oxide can be obtained at low temperatures (below 78 K) as a result of the reaction of SO3 and atomic oxygen or the photolysis of SO3 in a mixture with ozone.

Lower sulfur oxides are a group of chemical compounds, which include:

• SO (sulfur oxide and its dimer S2O2);
• S2O;
• Mono-oxides of sulfur SnO (are cyclic compounds consisting of rings formed by sulfur atoms, n can be from 5 to 10);
• S7O2;
• Polymeric oxides of sulfur.

Interest in lower sulfur oxides has increased. This is due to the need to study their content in terrestrial and extraterrestrial atmospheres.