File:On Vapour-Pressure and Osmotic Pressure of Strong Solutions (1908) (14801699903).jpg

Identifier: philtrans08812111 (find matches)
Title: On Vapour-Pressure and Osmotic Pressure of Strong Solutions
Year: 1908 (1900s)
Authors: Callendar, H.
Subjects: Proceedings of the Royal Society of London Philosophical Transactions of the Royal Society
Publisher: Royal Society of London

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re plotted against the values of n doubled. The curve (K) for KCl, which is of quite a different character, agrees verywell with the degree of ionisation deduced from the electric conductivity, onthe hypothesis that each of the 71 molecules takes one molecule of water.The curve for NaCl would coincide very closely with that for KCl if eachmolecule of NaCl took two molecules of H2O, but the observations forISTaOl do not appear to extend beyond n = 1*8. In plotting these observationsn is not doubled and the initial slope is 2*066 owing to the ionisation. * Zeit. Phys. Chem., vol. 4, p. 42, 1889. 2 M 2 492 Prof. H. L. Callendar. On Vapour-pressure and (Mar. 10, Rise of the Boiling-jpoint. 17. The rise of the boiling-point affords a means of verifying the theory ata different temperature, but the method is more difficult of application, andthe available observations less numerous than in the case of the depressionof the freezing-point. Kahlenbergs data for cane-sugar, KCl and ISTaOl,* are
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o 4 5 6 7 % 9 10 11 11 12^ H i5 16 17 Fig. 8.—Rise of the Boiling-point in Aqueous Solutions. ^8 plotted in the diagram, fig. 8. The curve a = 0 gives the relation betweenthe vapour-pressure ratio (i>—pO/i^^ ^^^ ^^^ ^^^^ ^^ temperature t abovethe boiling-point. The straight line t = 0*288 n corresponds to Yant Hoffsebullioscopic constant, the error of which is about 8 per cent, at ^ = 10.The observations (S) on the rise of the boiling-point for solutions of cane- •^ L. Kahlenberg, Journ. Phys. Chem., vol. 6, p. 362, 1901. 1908.) Osmotic Pressure of Strong Solutions, 493 sugar agree very fairly with the curve a = 5 up to a concentration ofbetween 5 and 6 molecules of sugar to 100 of H^O, which is about the limitof good agreement in fig. 5. It is perhaps remarkable that the number ofH2O molecules to one of sugar should apparently be the same at 100° C. as at0° G. Beyond this point, as in fig. 5, the degree of hydration a appears todiminish, being about 4 on the average at ^^

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