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Home >> Chemistry Dictionary >> Deutrium Heavy Hydrogen Diamagnetism
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Detonation. A type of explosive typified by a much-increased reaction rate as well as a very high velocity percussion wave and a high pressure rise. Very high localized temperatures are produced.
This type of explosive is important in engines where denotation can vary from an incipient stage, often referred to as pinking, to a more severe condition known as knocking.
Deutrium (heavy hydrogen). Symbol D. The isotope of hydrogen that has a mass number 2 (r.a.m. 2.0144). Its nucleus contain one proton and one neutron. The abundance of deuterium in natural hydrogen is about 0.015%. It is present in water as the oxide, deuterium oxide (see heavy water), from which it is usually obtained by electrolysis or fractional distillation.
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Its chemical behaviour is almost identical to hydrogen although deuterium compounds tend to react rather more slowly than the corresponding hydrogen compounds. Its physical are slightly different from those of hydrogen, e.g. b.p. 2.36 K (hydrogen 20.4 K).
Deuton. The nucleus of the deuterium atom. Used in linear acceleration for bombarding other nuclei.
Devtirification. Loss of the amorphous nature of glass as a result of crystallization.
Dewar flask. A vessel for storing hot or cold liquids so that they maintain their temperature independently of the surroundings.
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Heat transfer to the surroundings is reduced to a minimum : the walls of the vessel consist of two thin layers of glass (or, in large vessels, steel) separated by a vacuum to reduce conduction and convection; the inner surface of a glass vessel is silvered to reduce radiation; nd the vessel is stoppered to prevent evaporation. It was devised around 1872 by the British Physicist. Sir James Dewar (1842-1923) and is also known by its first trade name Thermos flask.
Dewaxing. Removal; of wax from lubricating oil stock.
Dextran. A mucilaginous polymer of glucose made by certain bacteria.
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It has mol. Wt. between 30,000 and 250,000, and has both 1-4 and 1-6 linkages with branches about every five units, giving it considerable resistance to enzymic hydrolysis. Manufactured by the fermentation of sucrose. It can be used as a plasma substitute in blood transfusions, as For cross-linked dextran see Sephadex.
The sodium salt of sulphuric acid esters of dextran are used as anticoagulants for the same purposes as heparin.
Dextrins. Intermediate products form during the hydrolysis of starch to sugars. They are strongly dextrorotatory. Manufactured by the action of heat and hydrolytic agents on wet or dry starch and used as adhesives
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Dextro. (d). An optically active compound rotate the plane of polarized light oon right hand side.
Dextrorotatory. Denoting a chemical compound that is able to rotate the plane of polarization of plane polarized light to the right (clockwise as observed by someone facing the one coming radiation).
Dextrose (Grape sugar, C6H12O6). A white crystalline solid (m.p. 419 k) sweet in taste. It is optically active and is Dextro-rotatory, have the name dextrose. It contains aldehydic group. It is used in medicine and as sweetening agent. It is also used in fruit preservations.
Diagonal relationship. A similarity ( in solubility and thermal stability) between compounds of elements of the main groups related to one another diagonally (Li. And Mg; Be and Al.).
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Results from a similarity in size in combining forms.
Dialin. The trivial name given to each isomer (two) of dihydronaphthalene.
Dialysis. The process of separating a crystalloid from colloid by diffusion or filteration through a membrane.
Diamagnetism. The property of all the substances that causes repulsion of the substance from a magnetic field. Originates in the interaction of the electronic charge and the field and is an additive property of the atoms and groups present. Order of magnitude 10-3 that of paramagnetism so that the effect is swamped by the presence of unpaired electrons.
1, 6-Diaminohexane, hexamethylene diamine, H2N.(CH2)6.NH2. Colourless solid when pure; m.p. 41°C,. b.p. 204°C. Manufacture by the electrochemical combination of two molecules of acrylonitrile to adiponitrile followed by catalytic reduction, or by a series of steps from cyclohexanone via adipic acid. Used in the production of Nylon [6,6]
Diamond. The hardest known mineral (with a hardness of 10 on Mohs’ scale). It is an allotropic from of pure carbon that has crystallized in the cubic system, usually as octahedral or cube, under great pressure. Diamond crystals may be colourless and transparent are yellow, brown or black. They are highly prized as gemstones but also have extensive uses in industry, mainly for cutting and grinding tools. Diamonds occur in ancient volcanic pipes of kimberlite; the most important deposits are in South Africa but others are found in Tanzania, the USA, Russia, and Australia. Diamonds also occur in river deposits that have been derived from weathered kimberlite, notably in Brazil, Zaire, Sierra Leone, and India. Industrial diamonds are increasingly being produced synthetically.
Diamond is very resistance to chemical reagents; potassium dichromate and sulphuric acid attack it with the formation of CO2. It burns in air or oxygen at 700°C to CO2 leaving scarcely any ash; some forms of bort may leave as much as 4.5% ash. Very high temperature and pressure on graphite in the presence of a metal catalyst gives synthetic diamonds big enough for many industrial uses.
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