Hydrogen is the simplest chemical element , is clear colorless gas tasteless and smell. It is the lightest gas ever (14.5 times lighter than air). Molecular hydrogen is relatively stable and is also less reactive due to the high bond energy. His thermal conductivity is seven times larger than air. The molecules are extremely small and therefore pass easily porous fabric.
In water sa vodík rozpúšťa nepatrne: V 1 litri vody sa pri 0 °C a tlaku 0,1 MPa rozpustí 22 ml plynného vodíka. Lepšie sa rozpúšťa v nikli, paládiu a v platine. Pri rozpúšťaní v týchto metal in molecule hydrogen fission at Atoms. Atomic hydrogen is more reactive than molecular hydrogen, so the reaction of hydrogen in the presence of these metals is faster. Nickel, Palladium and Platinum they are therefore excellent Catalyst.
Reactions with non-metals
At normal temperature, hydrogen combines with fluorine to form Hydrogen fluoride HF, even in the dark. WITH Chlorine forms Hydrogen chloride HCl only on Sunlight using Ultraviolet radiation or when the mixture Burning. Mixed with air or Oxygen combines after ignition on water.
Reakcia prebieha veľmi prudko, výbušne. Teplota vodíkového plameňa je veľmi vysoká (až 2 800 °C). Preto sa používa na Welding and metal cutting. At higher temperatures and in the presence of Catalysts hydrogen combines with Nitrogen on Ammonia.
It is further produced from it Nitric acid and nitrogen fertilizers.
Reactions with metals
It combines with most elements only at elevated temperature or in the presence of catalysts.
Hydrogen reactions are usually accompanied by the release of heat (Exothermic reaction) and sometimes a light effect - burning.
They are significant Reduction Properties of hydrogen used in the production of certain metals from their oxides:
In contrast, atomic hydrogen (so-called hydrogen in the nascent state) is very reactive and reacts with a wide range of substances even at low temperatures.
Hydrogen has a number of important uses. Such as the position in the production of various chemical compounds (Ammonia NH3, Nitric acid HNO3, methyl alcohol CH3OH, various nitrogen fertilizers), production of some metals (reduction of their oxides) or stiffening fats.
Used for Welding and metal cutting (oxygen-hydrogen flame). It is still used in a mixed ratio with nitrogen as a protective atmosphere in the firing of powder metallurgy semi-finished products. Liquid hydrogen is used as Rocket fuel, but it can also be a power source for other devices. Hydrogen is transported and stored in cylinders marked with a red stripe.
We can also get hydrogen Electrolysiswhich contains a small amount of H2SO4 or NaOH to increase Electrical conductivity. The electrolysis is carried out in Hoffman's device, where hydrogen is excreted at the cathode.
In industry, hydrogen can be produced in several different ways, as in the laboratory.
Hydrogen is the most common element in the whole space and the third most common on Earth. It occurs freely as well as bound in compounds. Free hydrogen is found, for example, in a gaseous envelope Star. Free hydrogen does not occur on Earth under normal conditions and is therefore bound only in compounds. Most hydrogen is bound in water, which covers most of the earth’s surface, but is also bound in various Organic compound i Inorganic compound. It is also an important biogenic element.
Hydrogen has 3 isotopes.
The name heavy hydrogen is also used. It is not subject to radioactive transformation, it is common in nature. For 6,500 atoms of procussion, there is one deuterium atom. The nucleus of deuterium is called Deuterón - is part of the heavy water molecule D2O.
It has significant uses in the nuclear industry. It is very effective Moderator (neutron retarder).
The nucleus of tritium is unstable and disintegrates with Half-life 12.4 years when radiating a small amount of energy Beta radiation. It is created by the effect Cosmic radiation to a deuterium atom or explosion Hydrogen bomb. It is used, for example, to label organic substances in research.