S. A. Arrhenius

Hydrogen was recognized as the essential element in acids by H. Davy after his work on the hydrohalic acids, and theories of acids and bases have played an important role ever since. The electrolytic dissociation theory of S. A. Arrhenius and W. Ostwald in the 1880s, the introduction of the pH scale for hydrogen-ion concentrations by S. P. L. Sprensen in 1909, the theory of acid-base titrations and indicators, and J. N. Brdnsted s fruitful concept of acids and conjugate bases as proton donors and acceptors (1923) are other land marks (see p. 48). The di.scovery of ortho- and para-hydrogen in 1924, closely followed by the discovery of heavy hydrogen (deuterium) and... 

An early attempt to provide a framework to observations on the chemistry of substances that react in water to produce acids or bases was provided by S. A. Arrhenius. At that time, the approach was limited to aqueous solutions, and the definitions of an acid and a base were given in these terms. Of course we now know that acid-base behavior is not limited to these cases, but it applies much more broadly. If we consider the reaction between gaseous HC1 and water,... 

S. A. Arrhenius defined an acid as any hydrogen-containing species able to release protons and a base as any species able to form hydroxide ions [71]. The aqueous acid-base reaction is the reaction between hydrogen ions and hydroxide ions with water formation. The ions accompanying the hydrogen and hydroxide ions form a salt, so the overall Arrhenius acid-base reaction can be written ... 

Immediately after the presentation of the van t Hoff equation, S. A. Arrhenius presented in 1889, on the analogy of the van t Hoff equation, Eq. (36), expressing the variation of the rate constant with temperature. He thus established simultaneously the concept of the activation energy as well. 

S. A. Arrhenius Draper s Tithonometer Bunsen and Roscoe s Actinometer Graham s Dialyser Stereoisomeric Lactic Acids Stereoisomeric Tartaric Acids Geometrical Isomerism... 

For the case where S = 2 this expression reduces to the simple exponential form of Arrhenius. For values of S greater than 2, it yields a much larger probability of reaction than one would obtain from the normal Arrhenius form. The enhancement may be several orders of magnitude. For example, when S = 10 and E/RT = 30, the ratio of the probability factor predicted by Hinshelwood s approach to that predicted by the conventional Arrhenius method is (30)4/4 = 3.375 x 104. The drawback of the approach is that one cannot accurately predict S a priori. When one obtains an apparent steric factor in excess of unity, this approach can often be used in interpretation of the data. 

Fig. 2.12 Examples of non-linear Arrhenius (or Eyring) plots (a) 1u(A oh)7 " ) vs T for the base hydrolysis of trans-Co(en)2ClJ. Curvature may result when k, k2 and A// , not equalling A// in the conjugate-base mechanism (Sec. 4.3.4). Reprinted with permission from C. Blakeley and M. L. Tobe, J. Chem. Soc. Dalton Trans. 1775 (1987). (b) nk vs T for iron removal from C- and N-terminal monoferric transferrin (lower and upper scales respectively). Transferrin contains two iron binding sites = 35 A apart. Either of the two sites, designated C- and N-terminal, can be exclusively labelled by Fe(lll) ions and these may be removed by a strong ligand such as a catechol (see Sec. 4.11). Reprinted with permission from S. A. Kretschmar and K. N. Raymond, J. Amer. Chem. Soc. 108, 6212 (1986). (1986) American Chemical Society.

C.A. Arrhenius, in 1787, noted an unusual black mineral in a quarry near Ytterby. Sweden, This was identified later as containing yttrium and rare-earth oxides. With the exception of promethium, all members of the Lanthanide Series had been discovered by 1907, when lutetium was isolated. In 1947. scientists at the Atomic Energy Commission at Oak Ridge National Laboratory (Tennessee) produced atomic number 61 from uranium fission products and named it promethium. No stable isotopes of promethium have been found in the earth s crust. 

Arrhenius, T. S., Blancharddesce, M., Dvolaitzky, M., Lehn, J. M., Malthete, J., Molecular devices - caroviologens as an approach to molecular wires synthesis and incorporation into vesicle membranes. Proc. Natl. Acad Sci. U. S. A. 1986, 83, 5355-5359. 

Pitsch, S., Eschenmoser, A., Gedulin, B., Hui, S. and Arrhenius, G. (1995). Mineral induced formation of sugar phosphates. 15. Chemistry of alpha-aminonitrile from the Zurich group. Origins Life Evol. Biosphere 25, 297. 

Process B was observed to pass through all three phase transitions, and it was found to be non-Arrhenius with distinct changes in its relaxation behavior delineated by the phase transitions. In the same manner as for Process A the characteristic relaxation time tb was extracted from the peak maximum of the dielectric losses, s"(a), T), (Fig. 21). 

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