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Home >> Chemistry Dictionary >> Gay Lussac's Law - Germanates
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Gas mask.
A method for protecting the face and breathing organs against poisonous gases. These include poisonous smokes, etc., used in chemical war fare. The air is drawn through a layer of activated carbon, which adsorbs vapours, and also through a filterpad, which retains solid particles of smokes. Such as arrangement is effective against was ‘gases’ and smokes, but not against gases of low molecular weight such as carbon monoxide or coal-gas.
Gasometer.
A very large iron vessel for the storing of coal gas.
Gas laws.
The laws which describe the behaviour of gases. These are Boyle’s law , Charles’s law, Gay-Lussac’s law of gaseous volumes and Avogadro’s hypothesis.
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Gas oil.
A petroleum distillate fraction intermediate between kerosene and light lubricating oil. It is used as a domestic and industrial fuel oil and as a feedstock for cracking processes.
Gay Lussac’s law 1.
When gases combine chemically the volumes of the reactants and the volume of the product, if it is gaseous, bear simple relationships to each other when measured under the same conditions of temperature and pressure.
GCMS.
Gas chromatography – mass spectroscopy.
Gd.
Gadolinium.
Ge.
Germanium.
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Geiger counter.
A device used to detect and measure amounts of radioactivity.
Gel.
A lyophilic colloid that has coagulated to a rigid or jelly – like solid. In a gel, the disperse medium has formed a loosely – held network of linked molecules through the dispersion medium. Examples of gels are silica get and gelatin.
Gelignite.
A form of dynamite used as an explosive.
Gel time.
The period required to form a soft gel as the initial stage in the strengthening of polymers by the use of glass fibre of rein forced plastic.
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Gem.
A prefix indicating that particular substituents are attached to the same atom, e.g. F3SiSiCl2SiF3, gem – dicholrohexafluorotrisilane.
Gemstones.
Material which because of their appearance and variety are used in jewellery and decoration. Synthetic stones simulate natural gemstones. Α – Alumina (corundum) gives ruby (with Cr3+) and sapphire (Fe plus Ti). Spinel, titania, SrTiO3 are also used but are virtually all artificial. Diamonds can be synthesized but are mainly used for cutting.
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Genins.
Where a glycoside is composed of a carbohydrate combined with a compound related in structure to the sterols, the non-carbohydrate portion of the molecules is called a ‘genin’. Genins include digiatalis, the toad venoms and the saponins, many of which have high cardiac activity. The latter are called cardiac aglucones.
Geraniol, 3, 7 –dimethy 1-2, 6-octadien -1-01.
A terpene alcohol; b.p. 229-2300C. Found in a very large number of essential oils. It can also be manufactured from turpentine. It is a colourless oil, smelling of roses, and is unstable in air. It forms citral – a on oxidation. By treatment with gaseous HCl geraniol is converted into limonene.
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Germanates.
Oxy compounds of germanium (IV) showing resemblances to simple silicates. E.g. SrGeO3 (cyclic [Ge3O9]6- and Mg2GeO4 (orthogermanate). Hydrated GeO2 dissolves in excess base to give [Ge(OH)6]2- and other oxide –hydroxide anions and cations.
Germanes, germanium hydrides.
Monogermane, GeH4, b.p.-880C; Ge2H6, b.p.-290C, and Ge3H8 are formed from GeO2 and LiAiH4 or NaBH4. Higher germanes, to Ge9H20, are formed by electric discharge on GeH4 Germanes are oxidized in air. An extensive chemistry of GeH3 – and related groups is known. Germanes have potentialities as sources of very pure Ge.
Germanium,
Symbol Ge. A lustrous hard metalloid element belonging to group IV of the periodic table; a.n. 32; r.a.m. 72.59; r.d. 5.36;m.p. 9370C; b.p. 28300C. It is found in zinc sulphide and in certain other sulphide ores, and is mainly obtained as a by –product of zinc smelting. It is also present in some coal (up to 1.6%). Small amounts are used in specialized alloys but the main use depends on its semiconductor properties. Chemically, it forms compounds in the +2 and +4 oxidation states, the germanium (IV) compounds being the more stable. The element also forms a large number of organometallic compounds.
German silver (nickel silver).
An alloy of copper, zinc, and nickel, often in the portions 5:2:2. It resembles silver in appearance and is used in cheap jewellery and cutlery and as a base for silver – plated wire, also electrum.
Germicide.
A material capable of destroying becteria.
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