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.

    54/200 (page 42)
    MOLECULES SIZE, VELOCITY, AND FREE PATH OF MOLECULES [contd.) MOLECULAR SIZE The molecular diameter <r has been calculated by the following formulae :— 1. The viscosity y of a gas is a function of the size of its molecules. y = ‘44pn/(V2Ntt<72) . . . Jeans <r = {‘09i2pG/(N?j)}^ 2. The thermal conductivity, k = i-6ycv - ‘^Spn^/No-2 <r = {-i46PG^/(N^ 3. Van der Waals’, b = 2irN<r3/3 <r = {3£/(2wN)}& 4. Limiting density, i.e. density D of densest known form, cr — {6/>/(7rDN)$ The values of p and y used in calculating G and L below are given on pp. 35, 41. The values of <r tabulated are mostly taken from Jeans’ “ Dynamical Theory of Gases,” or Rudorf {Phil. Mag., 1909, p. 795). Jeans takes N = 4 x 1019, while in the table following, the more recent value 2*75 X io19 has been used. Molecular diameters also follow from the properties of monomolecular films on liquids (see Langmuir). Ctas. O at 0 0 C. Mean free path, L. Molecular diameter it deduced from V h b It. p [ = D] cm./sec. cm. cm. cm. cm. cm. Hydrogen, H2. 18*39 x IO4 18*3 X IO“6 2*47 x IO-8 2-40 X IO-8 2-32 X IO~8 2*92 X IO-8 Helium, He 13-11 >» 28‘5 2*l8 it —- 2-30 4*34 „ Nitrogen, N2 . 4*93 »> 9*44 tt 3*50 a 3*31 a 3*53 tt 2*97 „ Oxygen, 02 4-61 a 9*95 tt 3*39 it 3‘II yy 2*79 „ Neon, Ne . . 5-61 tt 19*3 tt — — — Argon, A . . 4’i3 a 1 o'o tt 3*36 a — 2-86 tt 4*43 „ Krypton, Kr . 2-86 it 9*49 tt — — 3’H a 4*93 a Xenon, Xe . . 2*28 it 5 *61 yy — — 3*42 tt 488 „ Chlorine, Cl 3‘°7 tt 4*57 yy 4-96 tt — — Methane, CH4 6-48 tt 779 yy —- —- — — Ethylene, C2H4 4-88 tt 5*47 yy 4*55 it 4-68 a — 5*26 „ Carbon mon- oxide, CO . 4*93 tt 9*27 tt 3’5o it 3*3i a —- -— Carbon di- oxide, C02 . 3*92 tt 6-29 a CO tt 4‘32 a 3*40 tt 4*42 „ Ammonia,NH3 6-28 yy 6-95 — — Nitrous oxide, N20 . . . 3*92 tt 6*io yy 4*27 tt 4-20 a — 00 '-t- Nitric oxide, NO . . . 4-76 tt 9-06 yy 3*40 tt 3*40 a — —- Sulph. hydro- gen, H2S. . 4*44 v 5*90 yi — — — — Sulph. dioxide, S02 ... 3*22 tt 4*57 yy — — — — Hydrochloric acid, HC1 . 4*3o tt 6-86 a —• — — — Water, HaO . 7*08 tt 7‘22 tt 4-09 it 3*45 „ The formulae above assume the molecules to be spherical. Sutherland {Phil. Mag., 1910), adopting his formula (see p. 40) for the variation of y with temp., obtains the following values of <r. Unit, lo~8 cm. 2*17 He 1*92 2’66 2*71 N„ 2‘95 3*33 NO 2'59 CO 2*74 CO, 2*90 C2H4 331 Cl, 3-76