Chemistry 125: Lecture 19 October 13, 2010 Oxygen and the Chemical Revolution Lavoisier’s Analysis (1789) Chronological treatments of organic chemistry often begin with Lavoisier, the father of modern chemistry. But his “Chemical Revolution” depended upon discoveries like those of Scheele, the Swedish apothecary who discovered oxygen and prepared the first pure samples of organic acids. Lavoisier’s “Traité Élémentaire de Chimie” launched modern chemistry with its focus on facts, ideas, and words. Lavoisier weighed gases and measured heat with a calorimeter, as well as clarifying chemical language and thought. Lavoisier’s key concepts were conservation of mass for the elements, and “oxidation”, which could convert a “radical” or “base” into an acid. Elemental analysis was the technique for determining the composition of organic compounds. Lavoisier's early combustion and fermentation experiments showed a new, though naïve, attitude toward handling experimental data. For copyright notice see final page of this file

Carl Wilhelm Scheele ( ) Prerevolutionary Pharmacist Carl Wilhelm Scheele ( )

Scheele's Acids Benzoic Uric Citric Lactic Oxalic Gum Benzoin Rhubarb (?) Lemon Milk Urine (purified as heavy-metal salts) Bismuth, cobalt, antimony, tin, mercury, silver, and gold were attacked by lactic acid either by digestion or by boiling. After standing over tin the acid caused a black precipitate to form in a solution of gold in aqua regia. 7) Lead dissolved after several days of digestion. The solution acquired a sweet, tart taste but did not crystallize. 10) With copper our solution first took on a blue color, then green, finally dark blue, but it did not crystallize. 9) Iron and zinc were dissolved with formation of flammable air. The iron solution was brown and gave no crystallization, but the zinc solution crystallized. 8) On Milk and its Acid (1780) 19 pp. ! Tartaric Tartar (wine cask residue)

e.g. "Oxymoron" "Oxy" = Sharp What's sharp about Rhubarb? Acidic taste "acre" to be sour root "ac-" sharp sharp dullness (self-contradiction) Latin "acidus”; Greek (oxus)

Scheele's Acids (purified as heavy-metal salts) Benzoic Oxalic Citric Lactic Uric Tartaric Gum Benzoin Rhubarb Lemon Milk Urine Tartar (Wine Casks)

vs. Carboxylic Acid Alcohol pK a ~16Carboxylic Acid pK a ~5 Alcohol Carbonyl High HOMO Stabilized Higher HOMO More Stabilized (Note: there will be more to this story involving "inductive effects") pK a depends on energy difference between A-H and A - H +

Scheele's Acids (purified as heavy-metal salts) Benzoic Oxalic Citric Lactic Uric Tartaric Gum Benzoin Rhubarb Lemon Milk Urine Tartar (Wine Casks) ?

Uric Acid Two C=O LUMOs stabilize the High HOMO of N Two C=O LUMOs stabilize the Higher HOMO of N - pK a 5.8 (vs. 38 for NH 3  NH H + )

tung sten 7 Elements Discovered or Codiscovered by Scheele nitrogen chlorine manganese molybdenum bariumtungsten oxygen gases heavy stone (Swedish)

Scheele (1771) Feuerluft "fire air" Ag + O 2 > 340°C Ag 2 CO 3 Ag 2 O + CO 2  …since I have no large burning glass, I beg you to try with yours…

Genealogy Top

The Chemical Revolution 1789

Werad Radix Latin Licorice (glukos + rhiza) Greek Rutabega Swedish Wort Old English Mathematics (16th Cent) Race? Razza Italian Eradicate Wurzel German Chemistry (18th Cent - France) Politics (18th Cent - England) Radish Radical: Going to the root or origin = Root

1787: Radical Introduced as a Political Term "The necessity of a substantial and radical reform in the representation..." J. Jebb

September 17, 1787

by Louis Bernard Guyton de M ORVEAU ( ) "Radical" Introduced as a Chemical Term 1787 age 50

Méthode de Nomenclature Chimique 1787 Antoine François de F OURCROY ( ) age 32 Claude Louis B ERTHOLLET ( ) age 39

Antoine Laurent Lavoisier ( ) age 45 7,000 pounds (~$300,000) Traité Élémentaire de Chemie (1789)

Weighing a Gas vacuum Hg P atm - P gas

"Lavoisier in his Laboratory Mme. Lavoisier taking his dictation (After a sepia drawing by Mme. Lavoisier) " Lavoisier's Pneumatic Trough

Elementary Treatise of Chemistry 1789 PRESENTED IN A NEW ORDER AND ACCORDING TO MODERN DISCOVERIES With Figures

Preliminary Discourse (1789) I had no other object, when I began the following Work, than to extend and explain more fully the Memoir which I read at the public meeting of the Academy of Science in the month of April 1787, on the necessity of reforming and completing the Nomenclature of Chemistry. While engaged in this employment, I perceived, better than I had ever done before, the justice of the following maxims of the Abbé de Condillac, in his System of Logic, and some of his other works:

Preliminary Discourse (1789) "We think only through the medium of words. --Languages are true analytical methods. --Algebra, which is adapted to its purpose in every species of expression, in the most simple, most exact, and best manner possible, is at the same time a language and an analytical method. --The art of reasoning is nothing more than a language well arranged."

Preliminary Discourse (1789) Thus, while I thought myself employed only in forming a Nomenclature, and while I proposed to myself nothing more than to improve the chemical language, my work transformed itself by degrees, without my being able to prevent it, into a treatise upon the Elements of Chemistry.

Preliminary Discourse (1789) The impossibility of separating the nomenclature of a science from the science itself, is owing to this, that every branch of physical science must consist of three things; the series of facts which are the objects of the science, the ideas which represent these facts, and the words by which these ideas are expressed. Like three impressions of the same seal, the word ought to produce the idea, and the idea to be a picture of the fact.

Preliminary Discourse (1789) And, as ideas are preserved and communicated by means of words, it necessarily follows that we cannot improve the language of any science without at the same time improving the science itself; neither can we, on the other hand, improve a science, without improving the language or nomenclature which belongs to it. However certain the facts of any science may be, and, however just the ideas we may have formed of these facts, we can only communicate false impressions to others, while we want words by which these may be properly expressed.

Clarity: FactsIdeas Words “impressions of the same seal”

New Order 1) Doctrine 2) Nomenclature 3) Operations

Elements …if by the name of elements we mean to desig- nate the simple, indivisible molecules that make up substances, it is probable that we do not know what they are : but if, on the contrary, we associate with the name of elements, or of the principles of substances, the idea of the furthest stage to which analysis can reach, all substances that we have so far found no means to decompose are elements for us…they behave with respect to us like simple substances.

Traité É lémentaire de Chimie (1789) Table of Elements imponderable

Lavoisier-Laplace Calorimeter (1782) Flame 3 Feet Inner Can Completely Surrounded by Insulating Ice Lamp into Bucket Bucket into Cage Cage into Can Flame Completely Surrounded by Melting Ice Melted by Flame Only!

Elementary Treatise of Chemistry 1789 PRESENTED IN A NEW ORDER AND ACCORDING TO MODERN DISCOVERIES With Figures 1) Doctrine 2) Nomenclature 3) Operations New Order Ideas Words Facts

Facts: Analysis

Analysis

Since the chemical properties of the part of atmospheric air that does not support respiration were not well known, we were content to deduce the name of its base from the property of its gas to take the life of animals that breathed it : so we have named it azote, from the Greek privative , and from  (zoe) life, thus the unbreathable part of air would be azotic gas. besides it has been shown to enter also into nitric acid compounds; so one could be just as properly name it the nitrigen principle. Ultimately we had to reject a name which conveyed a systematic idea, & decided to avoid this risk of fooling ourselves by adopting the names azote and azotic gas, which expresses only a fact, or better a property, that of taking the life of animals that breathe this gas. We have given to the base of the portion of air that supports respiration the name of oxygen, deriving it from two Greek words (oxus), acid, & (geinomai), to cause to be, because in fact one of the most general properties of this base is forming acids by combining with most substances. We shall thus call oxygen gas the combination of this base with caloric. WORD FACT THEORY Caloric + Base or Radical Gas Oxy-gen + Base or Radical Acid we find ourselves forced to give a name. Nothing seems more convenient to us than hydrogen, that is to say, the generating principle of water, from (hydor) water, & from, (geinomai), to cause to be. We shall call the combinate of this principle with caloric hydrogen gas, & the word hydrogen alone will stand for the base of this same gas, the radical of water. Traité É lémentaire de Chimie (1789) ? The word gas is thus for us a generic name that designates the ultimate degree of saturation of whatever substance by caloric.

Lavoisier's Compound Radicals Scheele Acids

Oxidation States Radical 1° "oxide" 2° "-ous" acid 3° "-ic" acid 4° "oxygenated -ic" acid Risky Prediction

Elemental Analysis by Oil Combustion Air Supply Oil Supply H 2 O Collector CO 2 Collector Lamp H 2 O Collector

How to analyze a substance that will not burn cleanly? e.g. grape sugar Everyone knows how wine, cider and mead are made…

Plate X: Fermentation Apparatus H 2 O Absorption by CaCl 2 CO 2 Absorption by NaOH soln. any other Gas Foam catcher Sugar/Yeast/Water

I can consider the materials subjected to fermentation and the products of fermen- tation as an algebraic equation; and by in turn supposing each of the elements of this equation to be unknown, I can derive a value and thus correct experiment by calculation and calculation by experi- ment. I have often profited from this way of correcting the preliminary results of my experiments. Fermentation it can furnish a means of analyzing sugar Oxidation had failed with Air Oxygen Sulfuric Acid Mercuric Oxide etc. because of incomplete combustion (charring)

Lavoisier’s Bookkeeping 72 grains = 1 gros 8 gros = 1 ounce = g Proximate Ultimate

End of Lecture 19 Oct. 13, 2010 Copyright © J. M. McBride 2009,2010. Some rights reserved. Except for cited third-party materials, and those used by visiting speakers, all content is licensed under a Creative Commons License (Attribution-NonCommercial-ShareAlike 3.0).Creative Commons License (Attribution-NonCommercial-ShareAlike 3.0) Use of this content constitutes your acceptance of the noted license and the terms and conditions of use. Materials from Wikimedia Commons are denoted by the symbol. Third party materials may be subject to additional intellectual property notices, information, or restrictions. The following attribution may be used when reusing material that is not identified as third-party content: J. M. McBride, Chem 125. License: Creative Commons BY-NC-SA 3.0