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Home >> Chemistry Dictionary >>Flavin Adenine Dinucleotide - Fehling's Solution
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F.
Fluorine
F centre.
An anionic site in a crystal occupied only by an electron, e.g. NaCl plus Na vapour give blue Na1+xCl containing F centres.
Face centered cell.
A unit cell with lattice points at the cell corners and lattice points at the centres of the six cell faces. Only cubic and orthorhombic systems have crystals formed with face centred cells.
Face-centred cubic.
The cubic close-packed lattice (ccp).
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Face-centred lattice.
A lattice having an atom at the face-centre of each unit cell.
FAD (flavin adenine dinucleotide).
A coenzyme important in various biochemical reactions. It comprises a phosphorylated vitamin B2(riboflavin) molecule linked to the nucleotide adenine monophosphate (AMP). FAD is usually tightly bound to the enzyme forming a flavoprotein. It functions as a hydrogen acceptor in dehydrogenation reaction, being reduced to FADH2. This in turn is oxidized to FAD by the electron transport chain, thereby generating ATP (two molecules of ATP per molecule of FADH2).
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Fahl ore,
Cu3SbS3. Tetrahedrite
Fahrenheit scale. A temperature scale in which (by modern definition) the temperature of boiling water is taken as 212 degrees and the temperature of melting ice as 32 degrees. It was invented in 1714 by the German scientist G.D. Fahrenheit (1686-1739), who set the zero at the lowest temperature he knew how to obtain in the laboratory, (by mixing ice and common salt) and took his own body temperature as 96ºF. The scale is no longer in scientific use. To convert to the Celsius scale the formula is C=5(F-32)/9.
Fajan’s method.
The titration of Cl- with Ag+ using fluorescein as an adsorption indicator. At the end point the colour precipitate in red.
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Fajan’s rules.
Ionic compounds are most readily formed by:
(1) ions with low charge (e.g. Na+ more than Al3+);
(2) by large cations (Cs+ more than Na+);
(3) by small anions (Cl- more than I-).
Faraday.
(Symbol F). A unit of electric charge equal to the charge required to discharge one mole of singly charged ion. One Faraday is 9.648670×104 coloumbs.
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Farady’s laws of electrolysis. These state:
(1) the amount of decomposition during an electrolysis is proportional to the quantity of current passed;
(2) for the same quantity of electricity passed through different solutions the extent of decomposition is proportional to the chemical equivalent of the element of group liberated.
Faraday, unit.
The electrical charge of one mole of electrons. 1 Faraday = 96.487 coulombs.
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Farnesol.
C15H2, O 3, 7, 11-trimethy 1-dodeca-trans-2-trans 6, 10 trenaol Sesquiterpene alcohol found in many essential oils.
Images
B.p. 120ºC/0.3mm. Has a characteristic smell and is of value in perfumery. Oxidation gives the aldehyde farnesol. Farnesol is of importance in the biosynthesis of polyterpenoids including steroids.
Fat.
A mixture of lipids, chiefly triglycerides, that is solid at normal body temperatures. Fast occur widely in plants and animals as a means of storing food energy, having twice the calorific value of carbohydrates. In mammals, fat is deposited in a layer beneath the skin (Subcutaneous fat) and deep within the body as a specialized adipose tissue.
Fats derived from plants and fish generally have a greater proportion of unsaturated fatty acids than those from mammals. Their melting points thus tend to be lower, causing a softer consistency at room temperatures. Highly unsaturated fats are liquid at room temperatures and are therefore more properly called oils.
Fe.
Iron
Fehling’s solution.
A solution of copper sulphate, sodium potassium tartrate and NaOH used for estimating and detecting reducing sugars.
Feldspares.
A group of silicate minerals, the most abundant minerals in the earth’s crust. They have a structure in which (SiAl)O4 tetradedra are linked together with potassium, sodium, and calcium and very occasionally barium ions occupying the large spaces in the framework. The chemical composition of feldspares may be expressed as combinations of the four components:
anorthite (An), CaAl2Si2O8;
albite (Ab), NaAlSi3O8;
orteoclase (Or), KAlSi3O8; and
celsian (Ce), BaAl2Si2O8.
The feldspares are subdivided into two groups; the alkali feldspares (including microcline, orthoclase, and sanidine), in which potassium is dominant with a smaller proportion of sodium and negligible calcium; and the plagioclase feldspare, which vary in composition in a series that ranges from pure sodium feldspare (albite) through to pure calcium feldspare (anorthite) with negligible potassium. Feldspares from colourless, white, or pink crystals with a hardness of 6 on the Mohs scale.
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