Tables of physical and chemical constants and some mathematical functions / by G.W.C. Kaye and T.H. Laby.

  • G. W. C. Kaye
Date:
[1941]
Catalogue details

Licence: Public Domain Mark

Credit: Tables of physical and chemical constants and some mathematical functions / by G.W.C. Kaye and T.H. Laby. Source: Wellcome Collection.

    82/200 (page 70)
    LATENT HEATS LATENT HEAT OF FUSION The quantity of energy required to convert I gram of substance from solid into liquid without change of temperature. ICE Temp. Lt. ht. Observer, etc. 6-5° C. O 0 0 cals. 76-03 79*59 80-02 79*77 79-67 Pettersson, 1881. Regnault, 1843, corrected. Bunsen, 1870, with ice calorimeter. Smith, Phys. Rev., 1903 (in terms of 150 calorie taking Clark cell = 1*433 volts at 150 C.). (333*5 joules) Osborne N.B.S. 1939 (I.T. calorie 4-184 joules, 4-186 joules). VARIOUS SUBSTANCES Substance. Temp. Lt.ht. Substance. Temp. Lt.ht. Substance. Temp. Lt. ht Elements— °C. cals. Palladium 1550 36 Compounds— °C. cals. Aluminium f. 658 92*4 Phosphorus . 44 5 NH, . . . “75 108 Antimony * . 625 24*3 Platinum . . 1750 27 NaN03 . . 333 45‘3 Bismuth*. . 269 I3-0 Potassium 62 16 KN03 . . . 308 25*5 Cadmium. . 321 H Silver . . . 960 22 H2S04 . . . 10*3 24 Copper. . . — 43 Sodium (G.) 97*6 27*5 Acetic acid . 4 44 Lead . . . 327 5 Sulphur . . 115 9 Benzene . . 5*4 30 Magnesium* 644 46-5 Tin* . . . 232 14-6 Glycerine. . 13 42 Mercury . . — 3 Zinc* . . . 418 26*6 Naphthalene. 80 35 * Griffiths and Awbery, 1926. + Awbery, 1939. G., Ezer Griffiths, 1914. LATENT HEAT OF VAPORISATION Latent heats are given as the number of gram calories required to convert 1 gram of substance from liquid into vapour without change of temperature. The latent heat of vaporisation vanishes at the critical temperature. Trouton’s Xlule.—The latent heat of vaporisation of 1 gramme molecule of a liquid divided by the corresponding boiling point (on the absolute scale) is a constant (C). C = 21 for substances of which both liquid and vapour are unassociated. If the liquid is associated, C 21 {e.g. water, C = 26) ; if the vapour is associated, C <( 21 {e.g. acetic acid, C = 15). [See Nernst’s “Theoretical Chemistry.”] STEAM Regnault’s equation connecting latent heat and temperature takes no account of the temperature variation of the specific heat of water (see p. 66). The equation gives values which are too large at low temperatures. The equations of Griffiths, Henning, and Smith have been reduced and are here expressed in terms of the I. T. calorie = 4-186 joules (p. 65). Griffiths’ and Smith’s results rest further on an attributed value of 1-433 volts for the e.m.f. of the Clark cell at 150 C. See also next page. [The critical temp, of water is about 3740 C.] Observer. Regnault, 1847 . Griffiths, 1895 . Henning, A?m. d.Phys., 1906, 1909 . . . Smith, Phys A Rev., 1907 ./ Temp, range of expts. 63°~i94° C. 30° and 40° 3o°~ioo° ioo°-i8o° i4°-4o° Latent heat Lt at <° C. L t — 606-5 — *695^ Lt = 598-0 — -6052* SU = 599*1 - -60/, to -3% lor Lt — 94-2 (365 — /)3126, to U = 53871 — *6425^ — 100) — -03834(2* — ioo): L*= 596-9 - -580/ . T 0/ 1 /o