Amedeo Avogadro The Man, the Hypothesis, and the Number

Mario Morselli, Amedeo Avogadro, A Scientific Biography, Kluwer AcademicPublishers, USA, 1984.

Amedeo Avogadro was a very successful Italian lawyer, ..

Gay-Lussac has shown, twice as great as the volume of oxygen which enters into it, or, what comes to the same thing, equal to that of the hydrogen instead of being equal to that of the oxygen. But a means of explaining facts of this type in conformity with our hypothesis presents itself naturally enough; we suppose, namely, that the constituent molecules of any simple gas whatever (i.e., the molecules which are at such a distance from each other that they cannot exercise their mutual action) are not formed of a solitary elementary molecule, but are made up of a certain number of these molecules united by attraction to form a single one; and further, that when molecules of another substance unite with the former to form a compound molecule, the integral molecule which should result splits itself into two or more parts (or integral molecules) composed of half, quarter, &c., the number of elementary molecules going to form the constituent molecule of the first substance, combined with half, quarter, &c., the number of constituent molecules of the second substance that ought to enter into combination with one constituent molecule of the first substance (or, what comes to the same thing, combined with a number equal to this last of half-molecules, quarter-molecules, &c., of the second substance); so that the number of integral molecules of the compound becomes double, quadruple, &c., what it would have been if there had been no splitting up, and exactly what is necessary to satisfy the volume of the resulting gas.Thus, for example, the integral molecule of water will be composed of a half-molecule of oxygen with one molecule, or what is the same thing, two half-molecules of hydrogen.On reviewing the various compound gases most generally known, I only find examples of duplication of the volume relatively to the volume of that one of the constituents which combines with one or more volumes in the other.

Avogadro's Law states that equal volumes of all gases have the same number of molecules if each gas is at the same temperature and pressure.

Amedeo Avogadro: A Scientific Biography by M. …

Gay-Lussac'sresults did not by themselves reveal the formulas for hydrogen chloride andwater. The Italian chemist Amadeo Avogadro (1776-1856) developed the keyinsight that led to the exact formulas. He proposed that when gases aremeasured at the same temperature and pressure, equalvolumes of different gases contain equal numbers of gas particles. Avogadro's hypothesis, which explained Gay-Lussac'sresults, is summarized here and in part (b) in :

The most significant consequence of Avogadro's law is that the ideal gas constant has the same value for all gases.

AmedeoAvogadro (1776-1856) was an Italian physicist. He proposed in1811 his famous hypothesis, now known as Avogadro's law. The lawstated that equal volumes of all gases at the same temperature and pressurecontain the same number of molecules. Avogadro also distinguishedbetween an atom and a molecule, and made it possible to determine a correcttable of atomic weights.

This hypothesis became a law, now known as Avogadro's Law. Avogadro's hypothesis lay unnoticed for about fifty years.


Amedeo Avogadro – proposed Avogadro's law

Amedeo Avogadro (1776-1856; at the Edgar Fahs Smith collection, University of Pennsylvania) was an Italian chemist and physicist best known for today for Avogadro's law and Avogadro's number.

Amedeo Avogadro : a Scientific Biography (eBook, …

Avogadro did not discover or determine Avogadro's number; its determination occured late in the 19th century and early in the 20th and it was named in his honor.

Amedeo avogadro biography questions for kids

He is famed for his statement in 1811 of what isnow called Avogadro's Hypothesis that "equal volumes of all gases underthe same conditions of temperature contain the same number of molecules".

Amedeo Avogadro: Amedeo Avogadro ..

He experimented and discovered based off of well-known scientists' laws, theories, hypotheses, et cetera and his own ideas.

Another reason that Avogadro's Law and Number were not utilized for several years is because, much like Copernicus's ideas, people had a hard time accepting that they were accurate.

Amedeo Avogadro, in full Lorenzo Romano Amedeo Carlo Avogadro, ..


Interviewer: Ladies and gentlemen, we are honored to have visitors from19th century Italy, Count Amedeo Avogadro and his wife the Countess Felicita.

Avogadro | Feature - Chemistry World

Avogadro proposed his hypothesis in 1811. At that time there was no data at all on the number of paticles in a mole, or an agreement on any atomic weights or the standard. The first measurements which could give an approximate value for Avogadro's number were observations of brownian motion by Robert Brown in 1827.