Oxidation of oxygen is -2 in almost all known oxygen compounds . The oxidation state -1 is found in some compounds such as peroxides. The oxygen-containing compounds in other oxidation states are very rare: - / 2 (superoxides), - 1 / 3 (ozonides), 0 (element, hypofluorous acid), 1 / 2 (dioxygenyl), 1 (dioxygen difluoride), and 2 (oxygen difluoride).
Oxygen is reactive and will form oxides with all other elements except the noble gases of helium, neon, argon, and krypton.
Video Compounds of oxygen
Oxide
Water ( H
2 O ) is the most well known hydrogen oxide and oxygen compound. The properties are largely the result of the interaction of its component atoms, oxygen and hydrogen, with nearby water molecular atoms. The hydrogen atom is covalently bonded with oxygen in water molecules but also has an additional attraction (about 23.3 kJ Â · mol -1 per hydrogen atom) to adjacent oxygen atoms in separate molecules. This hydrogen bond between water molecules holds it about 15% closer than what is expected in a simple liquid only with Van der Waals forces.
Due to its electronegativity, oxygen forms a chemical bond with virtually all other free elements at high temperatures to produce an appropriate oxide. However, some elements, such as iron oxidizing iron oxide, or rust, Fe
2 O
3 , easily oxidized under standard conditions for temperature and pressure (STP). Metallic surfaces such as aluminum and titanium are oxidized in the presence of air and become coated with thin oxide films that migrate metal and slow down further corrosion. The so-called precious metals, such as gold and platinum, retain direct chemical combinations with oxygen, and substances such as gold (III) oxide ( Au
2 O
3 ) should be formed by an indirect route.
Alkali metals and alkaline earth metals all react spontaneously with oxygen when exposed to dry air to form oxides, and form hydroxides in the presence of oxygen and water. Consequently, none of these elements are found in nature as a free metal. Cesium is highly reactive with oxygen being used as a pickup in vacuum tubes. Although the solid magnesium reacts slowly with oxygen to the STP, it is capable of burning in the air, producing very high temperatures, and its metal powders can form explosive mixtures with air.
Oxygen is present as a compound in the atmosphere in small amounts in the form of carbon dioxide ( CO
2 ) and nitrogen oxide (NOT x ). Rock crust consists of most of silicon oxide (silica SiO
2 , found in granite and sand), aluminum (aluminum oxide Al
2 O
3 , in bauxite and corundum), iron (iron (III) oxide Fe
2 O
3 , in hematite and rust) and other metal oxides.
Maps Compounds of oxygen
Other inorganic compounds
Other parts of the earth's crust also form from oxygen compounds, the most important are calcium carbonate (in limestone) and silicates (in feldspar). Water-soluble silicates in the form of Na
4 SiO
4 , Na
2 SiO
3 , and Na
2 Si
2 O
5 is used as a detergent and adhesive.
Peroxides retain some of the original molecular structure of oxygen (& lt; ( - OO - .) White sodium peroxide or yellow light ( Na
2 O
2 is formed when metallic sodium is burned in oxygen Each oxygen atom in its peroxide ion may have a full octet of 4 pairs of superoxide electrons a class of compounds very similar to peroxides, but with only one unpaired electron for each pair of oxygen atoms ( O - 2 ) This compound is formed by oxidation of alkali metals by j the larger ionic radius (K, Rb, Cs). For example, potassium superoxide ( KO
2 ) is an orange-yellow solid that is formed when potassium reacts with oxygen.
Hydrogen peroxide ( H
2 O < br> 2 ) can be produced by passing a volume of 96% to 98% hydrogen and 2 to 4% oxygen through electrical discharges. A more commercial method is to allow the autoxidation of organic intermediates, 2-ethylanthrahydroquinone dissolved in organic solvents, to oxidize to H
2 O
2 and 2-ethylanthraquinone. 2-ethylanthraquinone is then reduced and recycled back into the process.
When dissolved in water, many metal oxides form an alkaline solution, while many nonmetallic oxides form an acid solution. For example, sodium oxide in solution forms a strong base of sodium hydroxide, while phosphorus pentoxide in solution forms phosphoric acid.
Anions are oxygenated like chlorate ( ClO - 3 ), perchlorate ( ClO -
4 ), chromate ( CrO 2- 4 ), dichromates ( Cr < span>
2 O 2 -
7 ), permanganat ( MnO -
4 ) , and nitrate ( NO - 3 ) is a strong oxidizing agent.Oxygen forms heteropoly acids and polyoxometalate ions with tungsten, molybdenum and some transition metals others, such as phosphotungstic acid ( H
3 PW < span>
12 O
40 ) and octadecamolybdophosphoric acid ( H
6 P
2 Mo
18 O < span>
62 ).
One of the unexpected oxygen compounds is dioxygenyl hexafluoroplatinate,
< sub style = "font size: inherit; line-height: inherit; vertical-align: baseline"> 2 PtF -
6 , found in studying the properties of platinum hexafluoride ( PtF
6 ). The change of color when the compound is exposed to atmospheric air suggests dioxidation dioxidation (in turn oxygen oxidation difficulties leads to the hypothesis that xenon may be oxidized by PtF
6 , resulting in the discovery of the first xenon xenon hexafluoroplatinate Xe
PtF -
6 ). Oxygen cations only form in the presence of stronger oxidants than oxygen, which limits them to fluorine action and certain fluorine compounds. Simple oxygen Fluor is known.
Organic compound
Among the most important classes of organic compounds containing oxygen are (where "R" is an organic group): alcohol (R-OH); ether (R-O-R); ketone (R-CO-R); aldehyde (R-CO-H); carboxylic acid (R-COOH); esters (R-COO-R); acid anhydride (R-CO-O-CO-R); amides (R-C (O) -NR 2 ). There are many important organic solvents containing oxygen, including: acetone, methanol, ethanol, isopropanol, furan, THF, diethyl ether, dioxane, ethylacetate, DMF, DMSO, acetic acid, formic acid. Acetone ( (CH
3 ) < br> 2 CO ) and phenol ( C
6 H
5 OH ) is used as feeder material in the synthesis of many different substances. Other important organic compounds containing oxygen are: glycerol, formaldehyde, glutaraldehyde, citric acid, acetic anhydride, acetamide, etc. Epoxides are the ether in which the oxygen atoms are part of the three-atom rings.
Oxygen reacts spontaneously with many organic compounds at or below room temperature in a process called autoxidation. The alkaline pyrogallol solution, benzene-1,2,3-triol, absorbs oxygen from the air, and is used in the determination of the atmospheric concentration of oxygen. Most organic compounds containing oxygen are not made by direct action of oxygen. Important organic compounds in industry and commerce are made by direct oxidation of precursors including:
- Ethylene oxide (used to make antifreeze ethylene glycol) is obtained by direct oxidation of ethylene:
-
- C
2 H < span>
4 Ã,½ O < span>
2 catalyst
-------> C
2 H
4 O
- C
- Peracetic acid (feeding material for various epoxy compounds) is obtained from acetaldehyde:
-
- CH
3 CHO O
2 catalyst
-------> CH
3 C (O) -OOH
- CH
Biomolecules
This element is found in almost all biomolecules that are important to, or generated by, life. Only a few common complex biomolecules, such as squalene and carotene, contain no oxygen. Of organic compounds with biological relevance, carbohydrates contain the largest proportion with oxygen masses (about 50%). All fats, fatty acids, amino acids, and proteins contain oxygen (due to the presence of carbonyl groups in the acid and ester residues). Furthermore, the seven amino acids inserted into the protein, have oxygen inserted into the side chains as well. Oxygen also occurs in phosphates (PO 4 3 - ) groups in important biological energy-carrying molecules ATP and ADP, in the spine and purines (except adenine) and pyrimidine RNA and DNA , and in bone as calcium phosphate and hydroxylapatite.
See also
- Oxygen
- Alotropes of oxygen
- Reactive oxygen species
References
- Cook, Gerhard A; Lauer, Carol M. (1968). "Oxygen". In Clifford A. Hampel. The Encyclopedia of Chemical Elements . New York: Reinhold Book Corporation. pp. 499-512. LCCN 68-29938 Ã,
Source of the article : Wikipedia
0 Comments