Chemistry 125: Lecture 20 October 20, 2010 Lavoisier’s Analysis (1789) Dalton’s Atoms (1801) Berzelius, Gay-Lussac, & Davy ( ) Wöhler’s Isomerism (1828) 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. The most prominent chemist in the generation following Lavoisier was Sweden’s J. J. Berzelius. Together with Gay-Lussac in Paris and Davy in London, he discovered new elements and improved Dalton’s atomic weights as well as combustion analysis for organic compounds. Invention of electrolysis led not only to discovering new elements but also to the theory of dualism, whichheld that elements were united by electrostatic attraction. Wöhler’s report on the synthesis of urea revealed a persistent naiveté about treating quantitative data. His discovery of isomerism made it clear that there was more to chemical substances than which atoms they contained and in what ratios. For copyright notice see final page of this file Preliminary

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

Lavoisier’s Bookkeeping Proximate Ultimate

Lavoisier’s Bookkeeping after before

Hydrogen Generator Red-hot Glass Tube Water 28 grains Carbon Water Water (less 85.7 grains) 144 cu. in. (100 grains) Carbonic Gas 380 cu. in. (13.7 grains) Flammable Gas Carbon + Water 28 gr gr. = Carbonic Gas + "Hydrogen" 100 gr gr. "I have thought it best to correct by calculation and to present the experiment in all its simplicity." from 28 gr. C (modern theory) Where did they go? + + = ! 1.38 g Traité pp

FactsIdeas Words Lavoisier Contributions Elements Conservation of Mass Oxidation Radical/Acid Salts Apparatus Quantitation Mass volume Substances Reactions Meaningful Names Element - Oxidation State - Salt Composition -ous, -ic, -ide, -ite, -ate Clarity

“[Chemistry's] present progress, however, is so rapid, and the facts, under the modern doctrine, have assumed so happy an arrangement, that we have ground to hope, even in our own times, to see it approach near to the highest state of perfec- tion of which it is susceptible.” Lack of Imagination

"It took them only an instant to make this head fall, but a hundred years may not suffice to make another like it." "Il ne leur a fallu qu’un moment pour faire tomber cette tête, et cent années peut-être ne suffiront pas pour en reproduire une semblable." Lavoisier Guillotined May 8, 1794 Age 50 "The Republic has no need of geniuses.” But all of his equipment (including 80 pounds of mercury) was seized for The People.

Boyle Lavoisier √ √

John Dalton Why do gases of different density remain mixed rather than stratifying? amateur meteorologist 1801 Continental European scientists proposed that different gases attract one another.

"the atoms of one kind did not repel the atoms of another kind" Atom “Heat Envelope” Matched Lines  Repulsion Mismatch  Reduced Repulsion Substitutes homorepulsion for heteroattraction

Atoms Explain Analyses: Definite Proportions Equivalent Proportions Multiple Proportions Pure compounds always have the same weight ratio of their elements. If a parts of A react with b parts of B, and a parts of A react with c parts of C, … If two elements form several compounds, their weight ratios are related by simple factors. and d parts of D react with b parts of B, then d parts of D react with c parts of C. =

Definite Proportions? Joseph Louis PROUST ( ) Claude Louis B ERTHOLLET ( ) NON!OUI ! metal alloys natural "organic" materials "chemicals" 

Multiple Proportions O/C O/N Oxides of Carbon%C%O Carbonic Acid (1801) Carbonous Acid (1789) Oxides of Nitrogen%N%O Nitrous Oxide (1810) Nitrous Gas (1810) Nitric Acid (1810) [1] [1] Rel. integral values consistent with simple atomic ratios %err of (O/C) vs. modern %err of (O/N) vs. modern Great scientists focus on the key factors despite errors. (Greatness : Key :: Chicken : Egg) ~2 ~4 ~2

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Berzelius etc. √

Berzelius Jöns-Jakob BERZELIUS ( ) Organic & Mineral Analysis Dualism (double decomposition) Electrolysis Notation for Composition Teaching, Writing & Editing Textbook (1808) 2000 compounds in 6 years! Good Atomic Weights for 50 elements!

Notation for Composition Alchemy Dalton Berzelius

Chemical Symbols of 1774 (Sweden) 1774 Symbols

“When only one combination of two bodies can be obtained, it must be pre- sumed to be a binary one, unless some other cause appear to the contrary.” Chemical Symbols of 1774 (Sweden) HO HN NO HC OC N 2 O NO 2 CO 2 CH 2 H N C O P S Mg Ca Na K Sr Ba Fe Zn Cu Pb Ag Pt Au Hg (Corresponding Berzelius Symbols) Dalton Notation (1808) NO 3 SO 3 SH 3 C 3 H “When four…one binary, two ternary, and one quarternary, &c. Latin (international) Analytical (NOT structural) Berzelius Notation (1811) Dalton’s Logic N 2 O NO 2 CO 2 CH 2 NO 3 SO 3 SH 3 C 3 H When three…a binary, and the other two ternary. ” “When two combinations are observed, they must be presumed to be a binary and a ternary…

Abbreviations: Dots denote O atoms = KO CrO 3 Superscripts denote numbers of atoms Benzoic should be H 10 C 14 O 3 (“acid” as anhydride) Didn’t catch on

Berzelius Jöns-Jakob BERZELIUS ( ) Organic & Mineral Analysis Dualism (double decomposition) Electrolysis Notation for Composition Teaching & Writing Textbook (1808) 2000 compounds in 6 years! Good Atomic Weights for 50 elements!

Atomic Weights and Equivalents

Dalton’s Atomic Weights (1808) Weights /1 /2 /3 /2 /3 /2 % err H 1 C 12 N 14 O 16 P 31 S 32

Silicon Chloride SiCl T. Thomson SiCl 2 L. Gmelin SiCl 3 J. J. Berzelius SiCl 4 Wm. Odling ?

Joseph Louis Gay-Lussac (1809) Oxidation of Sugar, etc. with NaClO 3 Cleans up Lavoisier's Mass Balance volumes of hydrogen per volumes of oxygen Water gives volumes of hydrogen per 1 volume of nitrogen Ammonia gives Alternative to Dalton's Law of Greatest Simplicity ,016 m (record for 50 years) ( ) Established that atmosphere composition is invariant with altitude.

Eilhard Mitscherlich ( ) Goniometer measures angles between crystal faces.

Relating Crystal Shape to Chemical Proportions (formula)

Isomorphism of (NH 4 ) 2 HAsO 4 / (NH 4 ) 2 HPO 4 ( ) Difference (1/10 °) (same shape)

Isomorphism provided definitive atomic weights ratios for some atom pairs. Need for relative atomic weights: Is water HO (Dalton) or H 2 O (Gay-Lussac) ? As atoms must play exactly the same role in arsenates that P atoms play in phosphates. 100 g of N,O,H combines with g P, or g As  As atom 2.55 times as heavy as P atom (neither nor 5.10 times as heavy)

Berzelius’s Table of atomic & molecular weights (1831) Weights

Based on O = 100 or H 2 = 1 O = [15.999] (-1.0%) (-1.0) (0.4) (1.3) Bars denote doubled atoms Scaled to modern discrepancy from modern value 10-fold increase in accuracy from Dalton!

Combustion Analysis

Berzelius Analysis (1) Tube 1/2” diameter (Fig 1) charged with dried powder containing: ~0.5 g of organic substance to be analyzed, 3 g NaClO 3 (Gay-Lussac’s O 2 source), 50 g NaCl (to moderate reaction by dilution). (2) Neck of tube heated and drawn out (Fig 2) (4) Assembled (Fig 6) so that gases (O 2, CO 2 ) that exit drying tube will bubble into bell-jar containing Hg with floating bulb (Fig 5) holding KOH (to absorb CO 2 ) and closed with permeable glove leather (to keep out Hg). Improved Method of Combustion Analysis (3) Joined (Fig 4) to water-collecting bulb (Fig 3) and CaCl 2 drying tube with rubber tubing

Berzelius Analysis (6) To be certain the KOH absorbs all of the CO 2 through the glove leather, wait 12 hours after the mercury stops rising in the bell jar before disassembling and weighing. (5) Build fire in brick enclosure to heat tube slowly from near end to far. Tube wrapped with metal sheet to keep it from popping when it softens at red heat under the pressure necessary to bubble through Hg. Improved Method of Combustion Analysis O2O2 KOH CO 2

Electricity

New York Public Library N 2 O at the Royal Institution London, 1802 Humphry Davy

Pile 1799 Volta Battery of Berzelius Humphry Davy Big Science at London’s Royal Institution Electrolysis CuZn “couple” 1.1 v 301 v 26 v 110 v 165 v

Davy (1808) I acted upon aqueous solutions of potash and soda, saturated at common temperatures, by the highest electrical power I could command, and which was produced by a combination of Voltaic batteries belonging to the Royal Institution, containing 24 plates of copper and zinc of 12 inches square, 100 plates of 6 inches, and 150 of 4 inches square… …though there was a high intensity of action, the water of the solutions alone was affected, and hydrogen and oxygen disengaged with the production of much heat and violent effervescence.

Davy (1808) The presence of water appearing thus to prevent any decomposition, I used potash in igneous fusion. By means of a stream of oxygen gas from a gasometer applied to the flame of a spirit lamp, which was thrown on a platina spoon containing potash, this alkali was kept for some minutes in a strong red heat, and in a state of perfect fluidity. The spoon was preserved in communication with the positive side of the battery of the power of 100 of 6 inches, highly charged; and the connection from the negative side was made by a platina wire. By this arrangement some brilliant phenomena were produced. The potash appeared a conductor in a high degree, and as long as the communication was preserved, a most intense light was exhibited at the negative wire, and a column of flame, which seemed to be owing to the development of combustible matter, arose from the point of contact.

Davy (1808) A small piece of pure potash, which had been exposed for a few seconds to the atmosphere, so as to give conducting power to the surface, was placed upon an insulated disc of platina, connected with the negative side of the battery of the power of 250 of 6 and 4, in a state of intense activity; and a platina wire, communicating with the positive side, was brought in contact with the upper surface of the alkali. …small globules having a high metallic lustre, and being precisely similar in visible characters to quick-silver, appeared, some of which burnt with explosion and bright flame, as soon as they were formed, and others remained, and were merely tarnished, and finally covered by a white film which formed on their surfaces.

Napoleon’s Response (via Gay-Lussac) Humphry Davy Big Science at London’s Royal Institution 600  1 kg Cu plates 600  3 kg Zn plates 2.6 tons of metal ~650 v “with that rapidity which characterised all his motions, and before the attendants could interpose any precaution, he thrust the extreme wires of the battery under his tongue, and received a shock which nearly deprived him of sensation. After recovering from its effects, he quitted the laboratory without making any remark, and was never afterwards heard to refer to the subject.” from: “The Life of Sir Humphry Davy, Bart.” 2,200 v LiBeB NaMgAl KCaGa RbSrIn CsBaTe

Electricity supplied more than new elements... It also supplied the organizing principle for Dualism

Chemical Symbols of 1774 (Sweden) 1774 Symbols Mix with Caustic Soda

"Double Decomposition" A B + C DA D + C B Explained by Electricity Dualism CuSO 4 2 NaOH Na 2 SO 4 Cu (OH) 2 ++ precipitate

“Electronegativity” First use in English (according to O.E.D.) 1837 J. D. Dana Syst. Mineral. 82 When chemistry has so far advanced, that the relative electro-negativity, (if I may so call it,) or electro-positivity, of the several elements, is fully known,..we shall probably be able to construct a natural arrangement of minerals on chemical principles. J. D. Dana son-in-law of Benjamin Silliman Dana House 1849

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Wöhler/Liebig

to J.J. Berzelius Heidelberg, 17 July, 1823 “Having developed the greatest respect for you through studying your writings, I have always thought it would be my greatest good fortune to be able to practice this science under the direction of such a man, which has always been my fondest desire. Although I earlier had planned to become a physician…”

With the greatest respect F. Wöhler from Frankfurt am Main

Friedrich Wöhler ( ) Letter to Berzelius (1837) “To see this old friend [Palmstedt] again, especially here [in Göttingen], was a real delight. He was just the same old guy, with the sole exception that he no longer wears the little toupee swept up over his forehead as he used to do.”

1828 Urea & Isomerism (problems for Monday, Oct see web readings)

Wöhler to Berzelius (1828) "Perhaps you still remember the experiment I carried out in that fortunate time when I was working with you, in which I found that whenever one tries to react cyanic acid with ammonia, a crystalline substance appears which is inert, behaving neither like cyanate nor like ammonia."

"Ammonium Cyanate" from Double Decomposition NH 4 Cl + Ag OCNNH 4 OCN + Ag Cl NH 3 NaOH OCNH H+H+ Pb ++ Pb(OCN) 2 HNO 3 Brilliant Crystal Flakes (Just like those from Urea + HNO 3 ) Not like an ammonium salt! Not like a cyanate salt!

Might Ammonium Cyanate Be Urea? Wöhler to Berzelius: "I recently performed a small experiment, appropriate to the limited time I have available, which I quickly completed and which, thank God, did not require a single analysis." Berzelius to Wöhler: "It is a unique situation that the salt nature so entirely disappears when the acid and ammonia combine, one that will certainly be most enlightening for future theory…"

Experimental Candor? Prout did dry-lab by making an approximate analysis and reporting results “corrected” by his theory! better than Berzelius’s Theory truncated instead of rounding up Urea had already been Analyzed Prout Atoms N C H O Total Dr. Prout (1817) Recalc. (from Berzelius) Discrepancies <2%  identical Dislectic Error ( & he didn't notice!) Prout’s Atomic Weight Theory: H = 1 ("protyle"  ) C = 6 ; O = 8 ; N = 14 Prout N 2 by volume: "6.3 cubic inches" ? (added wrong)  Modern Prout’s Experiment Moral: Don’t dry-lab! (like Lavoisier) Just Lucky?Prout’s theory was better than Berzelius’s experiments! Paragon of accuracy and honesty NH 4 OCN (calculated by Wöhler from Berzelius atomic weights)

? Ammonium Cyanate to Urea n ** n ** n ** poor overlap  probably intermolecular Can ammonium cyanate exist? Resonance Structures! NH 2 H2NH2N C O HH attack  * attack  * C=O very stable (lore)

Dunitz, Harris, et al. (1998)

Wöhler on Isomerism (1828) "I refrain from all the considerations which so naturally suggest themselves from this fact, especially in respect to the composition ratios of organic substances and in respect to similar elemental and quantitative compositions among compounds with very different properties, as may be supposed, among others, of fulminic acid and cyanic acid and of a liquid hydrocarbon and the olefiant gas, and it must be left to further investigations of many similar cases to decide what general laws can be derived therefrom."

On the Composition of Tartaric Acid and Racemic Acid (John's Acid from the Vosges Mountains), on the Atomic Weight of Lead Oxide, together with General Remarks on those Substances with have the Same Composition but Different Properties. by J. J. Berzelius (1830) "I have thought it necessary to choose between the words : homosynthetic and isomeric substances. The former is built from homos, equivalent, and synthetos, put together; the latter from isomeres has the same meaning, although it only properly says put together from the same pieces. The latter has the advantage with respect to brevity and euphony, and thus I have decided to choose it." "By isomeric substances I understand those which possess the same chemical composition and the same atomic [molecular] weight, but different properties." X-Ray showed that these crystals are Calcium Tartrate 4 H 2 O

There is more to chemistry than analytical C OMPOSITION! Now we know the importance of atomic arrangement, or STRUCTURE: C ONSTITUTION C ONFIGURATION C ONFORMATION but we need to be patient.

End of Lecture 20 October 20, 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