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Home >> Chemistry Dictionary >>Base Catalysed Reation - Backmann Thermometer
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Barytes.
The term used for an orthorhombic mineral form of barium sulphate BaSO4 the chief ore of barium. It is usually white but may also be yellow, grey or yellow.
Basalt.
A volcanic rock having 50% SiO2 16% Al2O3 and a number of other oxides. Used as building stone in the manufacture of glass and ceramics.
Base.
A compound that reacts with protonic acid to give water (and a salt) i.e. is a substance which furnishes hydroxyl ions. A more general definition which also applies to non-aqueous solutions, states that a base is a substance with tendency to gain protons. By this definition, OH- and the anions of weak acids, e.g. CH3COO-, are bases in aqueous solution.
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For ionized solvents which do not contain protons a base is a substance which reacts with the acid of that system to give a salt and the solvent. Thus the base KBrF4 reacts with the acid BrF2SbF6 to give the salt KSbF6 and BrF3 in bromine trifluoride.
A Lewis bas is a molecule with available electrons, e.g. ammonia.
As an adjective applied to metals base represents the opposite of noble, i.e. a base metal would be attacked by mineral acids.
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Base catalysed reaction.
The added reaction and Claiser condension is done in the presence of base, in which the first step is abstraction of a proton to give a carbonion.
Base metal.
A common relatively inexpensive metal, such as iron or lead, that corrodes, oxidizes, or tarnishes or exposure to air, moisture, or heat, as distinguished from precious metal, such as gold and silver.
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Base hydrolysis.
Hydrolysis in an alkaline medium, a ligand is replaced by hydroxyl group.
Basic.
A tendency of a substance to give OH- ions and the pH of the solution is greater than 7.
Basic oxide.
The metal oxides give basic solution when they are dissolved in water, e.g. Na2O, K2O
Na2O + H2O ----> 2NaOH(aq.)
Metal oxide(l) base
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Basic salt.
A compound which is regarded as being formed by replacing some of the oxide or hydroxide ions in a base by other negative ions. Basic salts are thus mixed salt oxides or salt hydroxide.
Basic slag.
Slag which is formed from a basic flux in a blast furnace. The basic flux is used to remove acid impurities in the ore and having calcium silicate, phosphate and sulphide. If the phosphorus content is high the slag can find use as a fertiliser.
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Bastnaesite.
A mineral, CeFCO3, used as a source of the lighter lanthanides.
Bathochromic
Shifts absorption to longer wavelength, lower frequency, lower energy. Compare hypsochromic.
Battery.
A number of electric cells joined together. The common car battery, or accumulator, usually consists of six secondary cells connected in series to give a total e.m.f. of 12 volts. A torch battery is usually a dry version of the Leclanche primary cell, to of which are often connected in series. Battery may also have cells connected in parallel, in which case they have the same e.m.f. as single cell but their capacity is increased. i.e. they will provide more total charge. The capacity of a battery is usually specified in ampere-hours, the ability to supply 1 A for one hr, or the equivalent.
Bauxite.
The chief ore of aluminium, consisting of hydrous aluminium oxides and aluminous laterite. It is a claylike amorphous material formed by the weathering of silicate rocks under tropical conditions. The chief producers are Australia, Brazil, Guinea, Jamaica, Russia, and Surinam.
Bcc.
Body-centred cubic.
B.C.F bromochlorodifluoromethane.
CBrClF2. A gas used in fire extinguishers.
Be.
Beryllium.
Bauxite.
The ore of aluminium which is essentially Al2O3 with additional water molecules. The ore is the combination of iron oxide and silica.
Beckmann thermometer.
A very sensitive mercury thermometer with a small temperature range which can be changed by transferring mercury between the capillary and a bulb reservoir. Used for accurate temperature measurements in the determination of molecular weights by freezing point depression or boiling point elevation.
Becquerel.
Symbol: Bq. It is the SI unit of activity.
Beeswax.
A mixture of mercyl palmitae, cerotic acid and esters and some paraffins produced by bees. Used in floor waxes, shoe polishes, leather treatment
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Behenic acid. n-docosanic acid.
C22H44O2CH3 . (CH1)20 COOH.m.p.80°C. A fatty acid occurring in oil of ben.
Beilstein’s test.
A method for detecting the presence of halogen in an organic compound. A piece of copper gauze is heated in an oxidizing flame until the flame is no longer tinged green; the compound is placed on the gauze, which is reheated. If Cl, Br or I is present the flame is tinged bright green.
Image P.No:59.
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