Hydrogen oxides
Hydrogen oxides are species that consist only of hydrogen (H) and oxygen (O). These are H 2 O n (n = 1, 2, 3, 4) and HO n (n = 1, 2, 3).
H 2 O for water is probably the world's best known empirical formula . Hydroxyl and hydroperoxyl radicals (OH or HO or HO 2 ) are summarized in atmospheric chemistry to form HO x .
In nuclear technology, “hydrogen oxides” usually mean H 2 O (water), D 2 O ( heavy water ) and T 2 O ( superheavy water ) as well as the species HDO, HTO and DTO occurring in mixtures.
water
Molecular hydrogen H 2 reacts exothermically with molecular oxygen O 2 to form water (H 2 O) in a molar ratio of two moles of H 2 to 1 mole of O 2 :
This so-called oxyhydrogen reaction releases 572.4 kJ / mol of energy.
If the two simple hydrogen atoms ( protium 1 H) are replaced by deuterium atoms that are twice as heavy , then heavy water (D 2 O) is obtained. If only one of the two H atoms has a deuterium nucleus, one correctly speaks of semi-heavy water (HDO); but often the term heavy water is also common. If it is not deuterium but tritium , one speaks of super-heavy water . These two forms of water have slightly different physical properties. For example, the melting point is 3.82 ° C and the boiling point is 101.42 ° C for heavy water and 4.48 ° C and 101.51 ° C for superheavy water, respectively. The chemical properties largely correspond to those of ordinary water, these two forms are only slightly less reactive.
Water probably plays the most important role in the functioning and viability of organisms. In the inanimate physiosphere , it is an important medium in geological and ecological elementary processes. Due to the role of water in relation to weather and climate, as a landscape designer in the course of erosion and due to its economic importance, among other things in the areas of agriculture, forestry and energy, it is also in many ways with history, economy and culture of human Connected to civilization. The science that deals with the spatial and temporal distribution of water and its properties is called hydrology .
Hydrogen peroxide
Hydrogen peroxide is an unstable compound made up of two hydrogen and two oxygen atoms (H 2 O 2 ). The compound can spontaneously break down into water and oxygen:
H 2 O 2 is very reactive and is therefore mixed with stabilizing substances. It is a popular oxidizing agent because the only byproduct is water.
More oxides
Another oxide is dihydrogen trioxide (H 2 O 3 ), which can be obtained by reacting ozone with 2-ethylanthraquinone at −78 ° C. The compound is even more unstable than H 2 O 2 and breaks down into water and oxygen at a temperature of −40 ° C.
Individual evidence
- ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 .