Chem 125 Lecture10/28/02

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Berzelius Analysis

(1) Tube 1/2” diameter (Fig 1) charged with dried powder containing ~0.5 g of organic substance, 3 g NaClO3 (O2 source), 50 g NaCl.(2) Neck of tube heated and drawn out (Fig 2) (3) Joined (Fig 4) to water collecting bulb (Fig 3)

and CaCl2 drying tube with rubber tubing

(4) Assembled (Fig 6) so that gas (O2, CO2) that exits drying tube bubbles into bell-jar containing Hg with floating bulb (Fig 5) holding KOH (to absorb CO2) and closed with permeable glove leather to keep out Hg. Wire attached to bottom so bulb can be retrieved from bell-jar.

(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 under pressure necessary to bubble through Hg when it softens at red heat.

Berzelius’sTable ofatomic & molecular weights

(1831) Weights

Based on O = 100 or H2 = 1

Bars denotedoubled atoms

O = 15.9994

[15.999]

0.998 (-1.0%)

14.162 (-1.0)

32.185 (0.4)

30.974 (1.3)

Abbreviations: Dots denote O atoms

= KO CrO3

Superscripts denote numbers of atomsBenzoic should be H10C14O3 (“acid” as anhydride)

Didn’t catch on

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