5- membered rings have ole for unsaturated and olane for saturated
compounds. Rules are given for naming compounds with two or more
different heteroatoms and for numbering the atoms. The system is
widely used both for monocyclic
compounds and for heterocyclic components of polycyclic compounds.
A
• Information about IUPAC nomenclature
hapticity Symbol η. The number of
electrons in a ligand that are directly
coordinated to a metal.
hard acid See hsab principle.
hard base See hsab principle.
hardening of oils The process of
converting unsaturated esters of
*fatty acids into (more solid) saturated esters by hydrogenation using a
nickel catalyst. It is used in the manufacture of margarine from vegetable
oils.
hardness of water The presence
in water of dissolved calcium or magnesium ions, which form a scum
with soap and prevent the formation
of a lather. The main cause of hard
water is dissolved calcium hydrogencarbonate (Ca(HCO 3 ) 2 ), which is
formed in limestone or chalk regions
by the action of dissolved carbon
dioxide on calcium carbonate. This
type is known as temporary hardness
because it is removed by boiling:
Ca(HCO 3 ) 2 (aq) → CaCO 3 (s) + H 2 O(l)
+ CO 2 (g)
The precipitated calcium carbonate is
the ‘fur’ (or ‘scale’) formed in kettles,
boilers, pipes, etc. In some areas,
hardness also results from dissolved
calcium sulphate (CaSO 4 ), which cannot be removed by boiling (permanent hardness).
Hard water is a considerable problem in washing, reducing the efÜciency of boilers, heating systems,
etc., and in certain industrial
processes. Various methods of water
softening are used. In public supplies, the temporary hardness can be
removed by adding lime (calcium hydroxide), which precipitates calcium
carbonate
Ca(OH) 2 (aq) + Ca(HCO 3 ) 2 (aq) →
2CaCO 3 (s) + 2H 2 O(l)
This is known as the Clark process (or
as ‘clarking’). It does not remove permanent hardness. Both temporary
and permanent hardness can be
treated by precipitating calcium carbonate by added sodium carbonate –
hence its use as a washing soda and
in bath salts. Calcium (and other)
ions can also be removed from water
by ion-exchange using zeolites (e.g.
Permutit). This method is used in
small domestic water-softeners. Another technique is not to remove the
Ca
2+ ions but to complex them and
prevent them reacting further. For
domestic use polyphosphates (containing the ion P 6 O 18
6–
, e.g. Calgon)
are added. Other sequestering agents
are also used for industrial water. See
also sequestration.
Hargreaves process See potassium sulphate.
harmonic An oscillation having a
frequency that is a simple multiple
of a fundamental sinusoidal oscillation. The fundamental frequency of a
sinusoidal oscillation is usually called
the Ürst harmonic. The second harmonic has a frequency twice that of
the fundamental, and so on.
harmonic oscillator A system that
oscillates with simple harmonic motion. The harmonic oscillator is exactly soluble in both classical
mechanics and quantum mechanics.
Many systems exist for which harmonic oscillators provide very good
approximations. Atoms vibrating
about their mean positions in molhapticity
264
h
www.AzShimi.ir www.AzShimi.com
compounds. Rules are given for naming compounds with two or more
different heteroatoms and for numbering the atoms. The system is
widely used both for monocyclic
compounds and for heterocyclic components of polycyclic compounds.
A
• Information about IUPAC nomenclature
hapticity Symbol η. The number of
electrons in a ligand that are directly
coordinated to a metal.
hard acid See hsab principle.
hard base See hsab principle.
hardening of oils The process of
converting unsaturated esters of
*fatty acids into (more solid) saturated esters by hydrogenation using a
nickel catalyst. It is used in the manufacture of margarine from vegetable
oils.
hardness of water The presence
in water of dissolved calcium or magnesium ions, which form a scum
with soap and prevent the formation
of a lather. The main cause of hard
water is dissolved calcium hydrogencarbonate (Ca(HCO 3 ) 2 ), which is
formed in limestone or chalk regions
by the action of dissolved carbon
dioxide on calcium carbonate. This
type is known as temporary hardness
because it is removed by boiling:
Ca(HCO 3 ) 2 (aq) → CaCO 3 (s) + H 2 O(l)
+ CO 2 (g)
The precipitated calcium carbonate is
the ‘fur’ (or ‘scale’) formed in kettles,
boilers, pipes, etc. In some areas,
hardness also results from dissolved
calcium sulphate (CaSO 4 ), which cannot be removed by boiling (permanent hardness).
Hard water is a considerable problem in washing, reducing the efÜciency of boilers, heating systems,
etc., and in certain industrial
processes. Various methods of water
softening are used. In public supplies, the temporary hardness can be
removed by adding lime (calcium hydroxide), which precipitates calcium
carbonate
Ca(OH) 2 (aq) + Ca(HCO 3 ) 2 (aq) →
2CaCO 3 (s) + 2H 2 O(l)
This is known as the Clark process (or
as ‘clarking’). It does not remove permanent hardness. Both temporary
and permanent hardness can be
treated by precipitating calcium carbonate by added sodium carbonate –
hence its use as a washing soda and
in bath salts. Calcium (and other)
ions can also be removed from water
by ion-exchange using zeolites (e.g.
Permutit). This method is used in
small domestic water-softeners. Another technique is not to remove the
Ca
2+ ions but to complex them and
prevent them reacting further. For
domestic use polyphosphates (containing the ion P 6 O 18
6–
, e.g. Calgon)
are added. Other sequestering agents
are also used for industrial water. See
also sequestration.
Hargreaves process See potassium sulphate.
harmonic An oscillation having a
frequency that is a simple multiple
of a fundamental sinusoidal oscillation. The fundamental frequency of a
sinusoidal oscillation is usually called
the Ürst harmonic. The second harmonic has a frequency twice that of
the fundamental, and so on.
harmonic oscillator A system that
oscillates with simple harmonic motion. The harmonic oscillator is exactly soluble in both classical
mechanics and quantum mechanics.
Many systems exist for which harmonic oscillators provide very good
approximations. Atoms vibrating
about their mean positions in molhapticity
264
h
www.AzShimi.ir www.AzShimi.com