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Count Lorenzo Romano Amedeo Carlo Avogadro di Quaregna e Cer
الأربعاء 6 يناير - 9:01
Count Lorenzo Romano
Amedeo Carlo Avogadro di Quaregna e Cerreto (August 9, 1776–July 9, 1856)
was an Italian scientist, most noted for his
contributions to the theory of molarity and molecular
weight. The number of molecules in one mole is called Avogadro's number
is honor of him, as is Avogadro's law.
Born in a noble
ancient family of Piedmont,
Avogadro was a brilliant student; he graduated in ecclesiastical law at a very
young age (20) and began to practice. However, soon after he dedicated himself
to the study of physics and mathematics, his preferred sciences, and in 1809
he started teaching them (then called positive philosophy) at a liceo
(high school) in Vercelli (where his family
had some properties).
During this stay in Vercelli he wrote a
concise note (memoria) in which he declared the hypothesis of what we
now call Avogadro's law:
equal volumes of gases, at the same temperature and pressure, contain the
same number of molecules;
this memoria he sent
to De Lamétherie's Journal
de Physique, de Chimie et d'Histoire naturelle and it was published in the
edition of July 14, 1811 with the title Essai d'une manière de
déterminer les masses relatives des molecules élémentaires des corps, et les
proportions selon lesquelles elles entrent dans ces combinaisons (complete
English text here: [1] ([ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط])
- First page: [2] ([ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط])).
Avogadro's Law
implies that the relationship occurring between the weights of same volumes of
different gases (at the same temperature and pressure) corresponds to the
relationship between respective molecular weights. Hence, relative molecular
masses can be calculated from the masses of gas samples.
Avogadro developed
this hypothesis after Joseph Louis
Gay-Lussac had published in 1808
his law
on volumes (and combining gases). The greatest difficulty Avogadro had to
resolve was the huge confusion at that time regarding atoms and molecules – one
of most important contributions of Avogadro's work was clearly distinguishing
one from the other, admitting that simple particles too could be composed of
molecules, and that these are composed of atoms. For instance, John Dalton didn't consider this possibility.
Avogadro did not actually use the word "atom" as the words
"atom" and "molecule" were used almost without difference.
He considered that there were three kinds of "molecules," including
an "elementary molecule" (our "atom"). Also, a keener
attention was given to the definition of mass,
as distinguished from weight.
In 1814
he published Mémoire sur les masses relatives des molécules des corps
simples, ou densités présumées de leur gaz, et sur la constitution de
quelques-uns de leur composés, pour servir de suite à l'Essai sur le même
sujet, publié dans le Journal de Physique, juillet 1811 ([3] ([ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط])),
about gas densities.
In 1820
he became a professor of Turin's university; In 1821
he published another memoria, Nouvelles considérations sur la théorie des
proportions déterminées dans les combinaisons, et sur la détermination des
masses des molécules des corps and little after Mémoire sur la manière
de ramener les composès organiques aux lois ordinaires des proportions
déterminées.
With suspicious
enthusiasm, he took part in political revolutionary movements of 1821
(against the king of Sardinia), so two years
later he was removed from his position (or, as it was officially declared, the
university was very glad to allow this interesting scientist to take a rest
from heavy teaching duties, in order to be able to give a better attention to
his researches). However, over time this political isolation was gradually
reduced, since revolutionary ideas were receiving increasing attention from Savoy
kings, up to 1848 when Charles Albert
granted a modern Constitution (Statuto Albertino). Well before this,
following the increasing attention to his works, Avogadro had been recalled at Turin university in 1833,
where he taught for another twenty years.
In 1841
he completed and published his work in Fisica dei corpi ponderabili, ossia
Trattato della costituzione materiale de' corpi, 4 volumes.
Very little is known
about his private life and his political activity; despite his unpleasant
aspect (at least as depicted in the rare images found), he was known as a
discreet tombeur de femmes although devoted to a sober life and a
religious man. He had six children. Several historical studies would confirm
that he had sponsored and helped some Sardinian plotters who were organising a
revolution in that island, stopped at the very last moment by the concession of
Charles Albert's statute. Some doubts however remain, considering the very
little amount of evidence.
Avogadro held public
posts in statistics, meteorology, and weights and measures (he introduced
decimal metric system in Piedmont) and was a
member of the Royal Superior Council on Public Instruction.
The scientific
society didn't reserve a great attention at his theory, so Avogadro's
hypothesis wasn't immediately accepted when announced. André-Marie Ampère
too was able three years later to achieve the same result by another method (in
his Sur la détermination des proportions dans lesquelles les corps se
combinent d'après le nombre et la disposition respective des molécules dont
leurs particules intégrantes sont composées), but the same indifferent
regard was given to his theories as well.
Only with studies by Gerhardt,
Laurent and Williamson on organic chemistry, was it possible to demonstrate
that Avogadro's law was indispensable to explain why same quantities of
molecules, brought to a vapour state, have the same volume.
Unfortunately, in the
performance of related experiments, some inorganic substances showed exceptions
to the law. The matter was finally concluded by Stanislao Cannizzaro,
as announced at Karlsruhe Congress (1860,
four years after Avogadro's death), where he explained that these exceptions
happened because of molecular dissociations which occurred at certain
temperatures, and that Avogadro's law could determine not only molar masses,
but as a consequence, atomic masses too.
Clausius, by his kinetic theory on gases, was
able to give another confirmation of Avogadro's law. Not long after, in his
researches regarding dilute solutions (and the consequent discovery of
analogies between the behaviour of solutions and gases), J. H. van 't Hoff
added his final consensus for the triumph of the Italian scientist, who since
then has been considered the founder of the atomic-molecular theory.
In honor of
Avogadro's contributions to the theory of molarity and molecular weights, the number of
molecules in one mole was renamed Avogadro's number.
Which is approximately 6.02214199 × 10²³
Amedeo Carlo Avogadro di Quaregna e Cerreto (August 9, 1776–July 9, 1856)
was an Italian scientist, most noted for his
contributions to the theory of molarity and molecular
weight. The number of molecules in one mole is called Avogadro's number
is honor of him, as is Avogadro's law.
Born in a noble
ancient family of Piedmont,
Avogadro was a brilliant student; he graduated in ecclesiastical law at a very
young age (20) and began to practice. However, soon after he dedicated himself
to the study of physics and mathematics, his preferred sciences, and in 1809
he started teaching them (then called positive philosophy) at a liceo
(high school) in Vercelli (where his family
had some properties).
During this stay in Vercelli he wrote a
concise note (memoria) in which he declared the hypothesis of what we
now call Avogadro's law:
equal volumes of gases, at the same temperature and pressure, contain the
same number of molecules;
this memoria he sent
to De Lamétherie's Journal
de Physique, de Chimie et d'Histoire naturelle and it was published in the
edition of July 14, 1811 with the title Essai d'une manière de
déterminer les masses relatives des molecules élémentaires des corps, et les
proportions selon lesquelles elles entrent dans ces combinaisons (complete
English text here: [1] ([ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط])
- First page: [2] ([ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط])).
Avogadro's Law
implies that the relationship occurring between the weights of same volumes of
different gases (at the same temperature and pressure) corresponds to the
relationship between respective molecular weights. Hence, relative molecular
masses can be calculated from the masses of gas samples.
Avogadro developed
this hypothesis after Joseph Louis
Gay-Lussac had published in 1808
his law
on volumes (and combining gases). The greatest difficulty Avogadro had to
resolve was the huge confusion at that time regarding atoms and molecules – one
of most important contributions of Avogadro's work was clearly distinguishing
one from the other, admitting that simple particles too could be composed of
molecules, and that these are composed of atoms. For instance, John Dalton didn't consider this possibility.
Avogadro did not actually use the word "atom" as the words
"atom" and "molecule" were used almost without difference.
He considered that there were three kinds of "molecules," including
an "elementary molecule" (our "atom"). Also, a keener
attention was given to the definition of mass,
as distinguished from weight.
In 1814
he published Mémoire sur les masses relatives des molécules des corps
simples, ou densités présumées de leur gaz, et sur la constitution de
quelques-uns de leur composés, pour servir de suite à l'Essai sur le même
sujet, publié dans le Journal de Physique, juillet 1811 ([3] ([ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط])),
about gas densities.
In 1820
he became a professor of Turin's university; In 1821
he published another memoria, Nouvelles considérations sur la théorie des
proportions déterminées dans les combinaisons, et sur la détermination des
masses des molécules des corps and little after Mémoire sur la manière
de ramener les composès organiques aux lois ordinaires des proportions
déterminées.
With suspicious
enthusiasm, he took part in political revolutionary movements of 1821
(against the king of Sardinia), so two years
later he was removed from his position (or, as it was officially declared, the
university was very glad to allow this interesting scientist to take a rest
from heavy teaching duties, in order to be able to give a better attention to
his researches). However, over time this political isolation was gradually
reduced, since revolutionary ideas were receiving increasing attention from Savoy
kings, up to 1848 when Charles Albert
granted a modern Constitution (Statuto Albertino). Well before this,
following the increasing attention to his works, Avogadro had been recalled at Turin university in 1833,
where he taught for another twenty years.
In 1841
he completed and published his work in Fisica dei corpi ponderabili, ossia
Trattato della costituzione materiale de' corpi, 4 volumes.
Very little is known
about his private life and his political activity; despite his unpleasant
aspect (at least as depicted in the rare images found), he was known as a
discreet tombeur de femmes although devoted to a sober life and a
religious man. He had six children. Several historical studies would confirm
that he had sponsored and helped some Sardinian plotters who were organising a
revolution in that island, stopped at the very last moment by the concession of
Charles Albert's statute. Some doubts however remain, considering the very
little amount of evidence.
Avogadro held public
posts in statistics, meteorology, and weights and measures (he introduced
decimal metric system in Piedmont) and was a
member of the Royal Superior Council on Public Instruction.
The scientific
society didn't reserve a great attention at his theory, so Avogadro's
hypothesis wasn't immediately accepted when announced. André-Marie Ampère
too was able three years later to achieve the same result by another method (in
his Sur la détermination des proportions dans lesquelles les corps se
combinent d'après le nombre et la disposition respective des molécules dont
leurs particules intégrantes sont composées), but the same indifferent
regard was given to his theories as well.
Only with studies by Gerhardt,
Laurent and Williamson on organic chemistry, was it possible to demonstrate
that Avogadro's law was indispensable to explain why same quantities of
molecules, brought to a vapour state, have the same volume.
Unfortunately, in the
performance of related experiments, some inorganic substances showed exceptions
to the law. The matter was finally concluded by Stanislao Cannizzaro,
as announced at Karlsruhe Congress (1860,
four years after Avogadro's death), where he explained that these exceptions
happened because of molecular dissociations which occurred at certain
temperatures, and that Avogadro's law could determine not only molar masses,
but as a consequence, atomic masses too.
Clausius, by his kinetic theory on gases, was
able to give another confirmation of Avogadro's law. Not long after, in his
researches regarding dilute solutions (and the consequent discovery of
analogies between the behaviour of solutions and gases), J. H. van 't Hoff
added his final consensus for the triumph of the Italian scientist, who since
then has been considered the founder of the atomic-molecular theory.
In honor of
Avogadro's contributions to the theory of molarity and molecular weights, the number of
molecules in one mole was renamed Avogadro's number.
Which is approximately 6.02214199 × 10²³
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