phere, especially by factory chim-
neys.faradSymbol F. The SI unit of ca-
pacitance, being the capacitance of a
capacitor that, if charged with one
coulomb, has a potential difference
of one volt between its plates. 1 F = 1
CV–1. The farad itself is too large for
most applications; the practical unit
is the microfarad (10–6F). The unit is
named after Michael *Faraday.
Faraday, Michael (1791–1867)
British chemist and physicist, who re-
ceived little formal education. He
started to experiment on electricity
and in 1812 attended lectures by Sir
Humphry *Davy at the Royal Institu-
tion; a year later he became Davy’s
assistant. He remained at the Institu-
tion until 1861. Faraday’s chemical
discoveries include the liquefaction
of chlorine (1823) and benzene (1825)
as well as the laws of electrolysis (see
faraday’s laws). He is also remem-
bered for his work in physics: in
1821 he demonstrated electromag-
netic rotation (the principle of the
electric motor) and in 1832 discov-
ered electromagnetic induction (the
principle of the dynamo).
Faraday constantSymbol F. The
electric charge carried by one mole
of electrons or singly ionized ions,
i.e. the product of the *Avogadro
constant and the charge on an elec-
tron (disregarding sign). It has the
value 9.648 5309(29) × 104 coulombs
per mole. This number of coulombs
is sometimes treated as a unit of elec-
tric charge called the faraday.
Faraday’s laws Two laws describ-
ing electrolysis:
(1) The amount of chemical change
during electrolysis is proportional to
the charge passed.
(2) The charge required to deposit or
liberate a mass m is given by Q =
Fmz/M, where F is the Faraday con-stant, z the charge of the ion, and M
the relative ionic mass.
These are the modern forms of the
laws. Originally, they were stated by
Michael *Faraday in a different form:
(1) The amount of chemical change
produced is proportional to the quan-
tity of electricity passed.
(2) The amount of chemical change
produced in different substances by a
Üxed quantity of electricity is propor-
tional to the electrochemical equiva-
lent of the substance.
fast-atom bombardment mass
spectroscopy (FAB mass spec-
troscopy) A technique in *mass spec-
troscopy in which ions are produced
by bombardment with high-energy
neutral atoms or molecules. It is used
for samples that are nonvolatile or
are thermally unstable.fatA mixture of lipids, chieÛy
*triglycerides, that is solid at normal
body temperatures. Fats occur widely
in plants and animals as a means of
storing food energy, having twice the
caloriÜc value of carbohydrates. In
mammals, fat is deposited in a layer
beneath the skin (subcutaneous fat)
and deep within the body as a spe-
cialized adipose tissue.
Fats derived from plants andÜsh
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 tempera-
tures. Highly unsaturated fats are liq-
uid at room temperatures and are
therefore more properly called *oils.fatty acidAn organic compound
consisting of a hydrocarbon chain
and a terminal carboxyl group (see
carboxylic acids). Chain length
ranges from one hydrogen atom
(methanoic, or formic, acid, HCOOH)
to nearly 30 carbon atoms. Ethanoic
(acetic), propanoic (propionic), and
butanoic (butyric) acids are impor-farad 220f