![]() So these - ous and - ic names, that we still use, come directly from Lavoisier.Īnd probably the next most important tool he developed was one for doing elemental analysis. But he has a more systematic name, showing its degree of oxidation. And oxygenated muriatic acid was - used to be called dephlogisticated marine acid. But he used, for example, oxygenated nitric acid, which was unknown. He didn’t use the peroxy acid, as we would often use nowadays. Okay? And then there was still a fourth degree of oxidation, which he called the oxygenated ic acid. For example, carbonous acid was not known at that time you see in the second entry in the second row, second column. And notice that many of these were not known and many of them still are not known because the theory wasn’t exactly right. So you have nitric acid, carbonic acid, sulfuric acid. And then you have a still higher degree of oxidation, the third degree, which is the - ic acid. Right? So you have, for example, nitrous acid, carbonous acid, sulfurous acid, phosphorous acid, he said. So that’s the lower oxidation state of an acid. And those names we use now, like cuprous, ferrous, come directly from this work of Lavoisier. So the second degree of oxidation, according to his theory, was to give an acid, that the suffix was to be systematically o-u-s, so - ous. But then there were further degrees of oxidation if you reacted with more oxygen. This was sort of a stretch, at least it seems so from our perspective, that caloric, heat, when it gets oxidized, yields oxygen gas. For example, hydrogen when oxidized would give water that’s the second row. So first you get an oxide, oxides of all the elements that are listed in the first table. ![]() There were several degrees of oxidation, as shown in this table from the English translation of his book. Right? And they could react with oxygen to become new things. There’s no doubt that the most important element for Lavoisier was oxygen, because of its key role in his chemistry, so that all other elements were called bases, or radicals. ![]() So now we’re going to look at some of the other developments from this book, in particular the idea of oxidation. For that he developed a calorimeter together with Laplace, and we saw how that worked by melting ice. But he also could measure heat, which didn’t have any weight. So we saw last time that he developed a - that in the process of developing a new nomenclature, he also developed instruments, so that he could weigh gases, because weighing turns out to be such an important feature in all of nineteenth century chemistry, no doubt the most important single technique. Which, you remember, he started work on just because he was interested in improving nomenclature, but found that there was such a tight coupling between nomenclature and the science - that is, the facts and the theory - that he couldn’t improve any one of them without improving the others. And it started with what we call the “Chemical Revolution”, which was launched by Lavoisier, with this book, in 1789, the same year as the French Revolution, The Elementary Treatise of Chemistry. Professor Michael McBride: Okay, as you may remember, way back before the exam, we’d started looking at how things really happened, how people were able to figure out about bonds, and how atoms were arranged, and molecules reacted, before there were the powerful techniques that we - that developed mostly in the last twenty-five or thirty years, as far as their practical application in organic chemistry but how they found these out before that time. The Development of Elemental Analysis: Lavoisier’s Early Combustion and Fermentation Experiments Freshman Organic Chemistry I CHEM 125a - Lecture 20 - Rise of the Atomic Theory (1790-1805)Ĭhapter 1.
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