Ketones are organic compounds of carbon, hydrogen and oxygen, where
the ketone functional group, >C=O is contained within the
molecule. The are the compounds which form a homologous
series which can be represented by the general
formula R.CO.R', where R and R' are alkyl groups, and may be
the same or different groups.
Ketones are formed by the oxidation of secondary alcohols.
[O]
R2CHOH ==> R.CO.R' + H2
Secondary Ketone
Alcohol
The chemistry of the ketones is governed largely by the presence
of the Carbonyl Group, >C=O. The polarity of this group means
that the electron-deficient carbon atom of the carbonyl
group is susceptible to attack by reagents which are
rich in electrons.
The first member of the homologous series of ketones is
acetone, CH3.CO.CH3. Other aliphatic ketones are
named by naming the groups attached to the carbonyl group
and adding the word ketone. Using systematic nomenclature,
the longest chain carrying the carbonyl group, >C=O, is made
the parent structure and compounds named by replacing
the "e" of the parent alkane by the suffix "-one". The
positions of substituents are indicated by numbers, where
the carbonyl carbon atom is allocated the lowest possible number.
Kinetic energy is the energy possessed by a body due to its motion.
The kinetic theory of gases explains the physical and thermodynamic properties of
gases as molecules in relatively unconstrained random motion, which are free to fill
completely the container in which they are contained.
Brownian Movement and the
observed diffusion of gases are vindications of this theory. The mathematical treatment
of the random motion of molecules was published by
Albert Einstein
in 1905AD and predicts properties which have been verified experimentally.
Postulates of the Kinetic Theory of Gases
The Kinetic Theory of Gases is a model that accounts for many
of the physical properties of gases. The main concepts of the
theory are :
- that a gas consists of small identical particles which
exert no forces on each other except at the instant of collision.
- that these particles move about at random and travel
in straight lines between collisions.
- that the collisions of particles with each other
and with the walls of the containing vessel are perfectly elastic.
- that the pressure of a gas is created by the
particles striking the walls of the container.
- that the size of a particle is negligible compared with
the volume of the container.
- that the particles are elastic, no energy is gained
or lost on collision. In an elastic collision the only
change in energy is the kinetic energy of the colliding
particle will gain kinetic energy and the other will
lose an equal amount.
The kinetic theory of gases is largely the result of the work
of Count Rumford, James Joule, and James Clark Maxwell.
Knocking is the premature spontaneous explosion of the
petrol mixture during the compression stroke in a
petrol engine before the mixture is ignited by a spark.
Knocking causes significant loss of power and may
result in damage to the engine.
Kohlrausch's Law states that the equivalent conductivity
of an electrolyte at infinite dilution is equal to the
sum of the ionic motilities of the ions produced by
the electrolyte.
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Elements ....
Compounds ....
Index
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