Physical chemistry for physicians and biologists / by Ernst Cohen ; authorized translation from the German by Martin H. Cohen.

  • Ernst Cohen
Date:
1903
Catalogue details

Licence: Public Domain Mark

Credit: Physical chemistry for physicians and biologists / by Ernst Cohen ; authorized translation from the German by Martin H. Cohen. Source: Wellcome Collection.

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    originally present has been decomposed. It is assumed that the products of the reaction, in this case arsenic and hydrogen, are removed as soon as formed. In the literature we often find equation (3) stated in a some- what different form. If the concentration of the substance under- going decomposition is equal to A at the beginning of the experi- ment (¢ = 0), and if the amount decomposed at the time ¢ is 7, then the concentration of the undecomposed substance at this time is A — x,, and this value is equal to C, in the equation (3). If the amount decomposed at the time ¢, equals x,, then A — 2, can be substituted for C,. Equation (3) then assumes the follow- ing form: 1 i A— 2, b= . ; Dei A — 2, The gradual decomposition of the hydrogen arsenide indicates that all the molecules of a gas do not exist in the same state; if they did, then the decomposition of all the molecules would occur simultaneously or not at all. B. BIMOLECULAR REACTION. A chemical reaction in which two molecules react with each other we call a bimolecular reaction. We choose as an example a reaction that has been of excellent ser- vice in the study of many weighty problems in physical chemistry,—the saponification of esters by bases. If we take the case in which ethyl acetate is saponified by sodium hydroxide, we can represent the reaction by the - following equation: CH,COOC,H,-+ NaOH =CH,COONa+ C,H,OH. If dilute aqueous solutions of ethyl acetate and sodium hydrate are mixed together, double decomposition can occur between the two dissolved substances only where
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