Avogadro bowl

temperature scale for gases, Avogadro's law, Avogadro's number

After the Italian physicist and chemist Amedeo di Quaregna e Ceretto, Count of Avogadro (Turin 1776-1856).

Following the example of his father, a lawyer and senator for Piedmont, Amedeo Avogadro studied law in Turin. He worked as a lawyer for five years. However, he and his brother became fascinated by Volta's work and the development of the first battery.

Together they studied electricity on their own. In 1806 Amedeo became a 'demonstrator' at the Academy of Turin, from 1809 a teacher of mathematics and physics at the Royal College of Vercelli, after 1820 professor of physics at the University of Turin.

In 1811 he formulated his famous hypothesis that equal volumes of different gases and vapors at equal pressure and temperature contain the same number of molecules: Avogadro's law.

So whether there is a light gas or a heavy gas in a room, there are always the same number of gas molecules in the room. This is in contrast to the suspicion that not as many large molecules fit in the chamber as small ones.

More generally, it turns out that a quantity of substance that weighs the same grams as its molecular weight (so, for example, 18 grams of water) always contains six hundred thousand trillion molecules - Avogadro's famous number: 6.02 x 1023.

Avogadro continued to publish about his invention, but no one responded. The chemists of his time did not believe it. The modest Avogadro devoted himself to his large family, published in rather obscure magazines and led a secluded life.

It was only when his compatriot Stanislao Cannizzaro showed what could be achieved with Avogadro's thinking at a chemistry conference in Karlsruhe in 1860 that the breakthrough came.

Also present at that meeting was the young Mendeleev (from the table), who was deeply impressed by Cannizzaro's speech. Count Avogadro had already been dead for four years.

> (see also Mendeleev)

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