Dictionary, Defintion, Meaning, What is Fluorescein, Fluorocarbons, Flocculating Agent, Flint Glass, Florisll, Flu Gas, Fluorescence, Fluoridation, Fluorimetry, Fluorinating Agent

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Home >> Chemistry Dictionary >>Fluorescein - Fluorocarbons

Your Ad Here	Flint glass: A type of glass having lead silicate. It is generally used for optical purposes. Flocculating agent. A material which forms a gelatinous precipitate on addition to water. The precipitate settles in the water and carries with if finely divided particulate matter which does not settle out of own accord. Florisll. Trade name of a magnesium silicate used for chromatography especially of fluorine-containing compounds. Flu Gas: The gaseous products of combustion from a boiler furnace consisting predominantly of carbon dioxide, carbon monoxide, oxygen nitrogen and steam. Analysis of the fine gases is used to check the efficiency of the furnace.
Fluorescein, C₂₀H₁₂O₃. A darked crystals with green iridescence. M.p. 314-316ºC (decomp.). It is made by heating phthalic anhydride with recorcinol. In alkaline solution it shows intense green fluorescence. It is a dyestuff and is used for colouring liquids in various instruments and by Water Authorities for determining the route of water supplies, leakages, etc. Fluorescence. Many substances absorb electromagnetic radiation, e.g. light or X-rays, of a certain wavelength. Par of the energy thus absorbed is re-emitted as radiation of longer wavelength. This process is known as fluorescence.
Fluoridation, The term used for process of adding very small amounts of fluorine salts e.g., sodium fluoride, NaF to drinking water to prevent tooth decay. Fluorimetry: An analytical technique using the fluorescent properties of the substance to be estimated. Fluorinating agent. A sabstance used to introduce F or replace e.g. H by F. Examples are F₂, KF, HF.	Your Ad Here
Fluorine: A pale greenish yellow gas prepared by the electrolysis of a solution of potassium hydrogen fluoride in anhydrous hydrogen fluoride. It is the most reactive of all the elements. Directly it combines with almost all other elements with extreme vigour forming fluorides. 2Na + F₂ --> NaF 2F2 + 2H₂O --> 4HF + O2 2Sb + 3F2 --> 2SbF₃ CCl₄ + F₂ --> CF₂Cl₂ + Cl₂ It is used to prepare Freon which is used as in refrigeration and as solvent for D.D.T. Its compounds, such as, sodium fluoride and cryolite are used as insecticides. A new plastic Teflon which is resistant to the action of acids, alkalies and oxidizing agents, is a polymarised tetrafluorethylene (F₂C=CF₂). Uranium hexafluoride (UF₆) is particularly used in separation of isotopes of uranium.
Your Ad Here	Fluorite. A mineral form of calcium fluoride, CaF₂ crystallising in the cubic system. Fluorimetry. Refers to the determination of substances from the intensity of fluorescene arising under UV irradiation. Fluorn acids: Complex fluoro salts are formed by most elements but the free acids are, in general not known (e.g. HF and BF₃ combine only in the presence of a base, e.g. NH₃)

Fluorocarbons:
Compounds obtained by replacing the hydrogen atoms of hydrocarbons by fluorine atoms. Their high stability to temperature makes them suitable for a variety of uses, including aerosol propellants, oils, polymers, etc. They are often known as freons. There has been some concern that their use in aerosols may cause depletion of the ozone layer.

Fluoroform:
The trivial name for CF₃H, trifluoromethane.

Fluorspar:
A naturally occurring form or calcium fluoride. (CaF₂)

Flux
(1) An additive assisting in fusion-e.g. CaCO₃ in iron-smelting-although the limestone also helps with slag formation.
(2) A substance enabling two pieces of metal to be joined without oxidation.

Fly ash.
Na₂CO₃. Sodium carbonate.

Fm.
Fermium.

Foamed plastics.
See cellular plastics.

Food value.
The energy released when a fuel of food is combusted.

Force constant.
A measure of the restoring force to vibration in a bond. Given by

V=1/C Force Constant

where n is the vibrational frequency, (cm^-1), f is the force constant, c is the velocity of tight and m is the reduced mass of the oscillator A-B(g). The stronger the bond the greater the force constant.

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