Atomic weight Bunsen

As his research advanced to the studies of gases and alkali metals, Bunsen recognized the importance of developing new methods to analyze and identify chemical substances. The importance of quantitative analysis was realized in the late eighteenth century. Chemists needed to probe further into a substance s composition in order to help explain the physical world. Bunsen recognized this need and worked to develop new instruments for this purpose. For example, he invented new types of galvanic and carbon-zinc electrochemical cells, or batteries, to isolate barium and sodium. He also constructed a new type of ice calorimeter that measured the volume, rather than the mass, of melted water. This allowed Brmsen to measure a metal s specific heat in order to find its atomic weight. 

Dc.xtcr in 1857 carried out some valuahlc work in Bunsen s laboratory to determine tho atomic weight of antimony. He carofully weighed out a small quantity of antimony and oxidised it with nitric acid, and finally heated tho residue until it was converted into ShjO.,. From 100 parts of Sh 0.j there were 79-28. (avcnige value) parts of Sh. Hence tho proportion ... 

As Mendeleev wrote in his article On the Placement of Cerium in the Periodic System of Elements To confirm the above ideas, I undertook the problem of determining the heat capacity of the above-mentioned metals. The experimental results, obtained in the fall of 1870, were confirmed by the investigations of Bunsen and spoke in the advantage of the corrected atomic weights. 

Following the adventurous story of terbium it is actually impossible to decide by now who was the true discoverer, Mosander, Delafontaine or Smith The element names, as indicated above were applied inconsistently, and we cannot know whether they referred to the same substance. Did Mosander find the same substance and called it erbium that finally became terbium with Delafontaine, or was Bunsen correct and consequently Mosander s fraction was a mixture only No data were reported that would allow us to state now, at this late date, what substances were identical, no characteristic spectral lines, no exact atomic weight values are at our disposal as yet. 

Bunsen isolated from Cadet s liquid a compoimd which he called alkarsiny the analysis giving the formula C4H12AS2. (He used Berzelius s atomic weights C = 12 25, O = 16, H = I, As=75.) He remarks that Berzelius suggested to him that it was probably C4H12AS2O, which would follow from the method of preparation from an acetate and arsenious oxide ... 

By closely studying the work of Kirchoff and Bunsen, Hinrichs found that some of the spectral hne frequencies, those referred to as dark hnes, could be related to the chemistry of the elements through their atomic weights, as well as to their postulated atomic dimensions. The difference between the spectral line frequencies seemed to be inversely proportional to the atomic weights of the elements in question. Hinrichs quoted the values of calcium, where the frequency difference is 4.8 units, and barium, which is chemically similar but has a higher atomic weight and shows a frequency difference of 4.4 units." ... 

Bessemer converter for steel manufacture. German chemists Robert Bunsen and Gustav Kirchhoff discover the element cesium. Scottish physicist James Clerk Maxwell and Austrian physicist Eudwig Eduard Boltzmann independently develop statistics for analyzing the behavior of molecules in a gas. Robert Bunsen invents the magnesium light. Italian chemist Stanislao Cannizzaro convinces an international conference of chemists to use the value of atomic weights determined by Swedish chemist Jons Jakob Berzelius to standardize chemical formulas. 

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