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.

    101/200 (page 89)
    OPTICAL ROTATIONS OPTICAL ROTATIONS OF PURE LIQUIDS AND SOLUTIONS At - the rotation in degrees (for light of some given wave-length) of the plane of polarization by a liquid when at the temperature t° C. lt = the length of the column of liquid in decimetres {i.e. io cms.). c p — the number of grams of active substance in ioo grams of solution. 1 q = (ioo — p) - the percentage (by weight) of inactive solvent in the solution. - p, = the density in grams per c.c. of the liquid or solution at t°. ct — ppt = the concentration expressed as grams of active substance per ioo l c.cs. of solution at t°. r i .jr. ... , , ,0\ rotation per decimetre of sol. [a]( = the specific rotation (at t°) -7—-t—^—r-—-=- grams of active substance per c.c. of sol. A For a pure liquid [a], = — , *tpt For an active substance in solution [a], = ~l(7~T~ Pi} — ‘ = ^7—*,since /, 1 \p + q J ltppt ltct ’ (P + q) = ioo. The rotation depends on the wave-length of the light used; it increases as the wave-length (A) diminishes (o oc i approx.), a also varies with the nature of the inactive solvent and with the concentration of the solution. The rotation is called positive or right-handed (dextro, d) if the plane of polarization appears to be rotated in an anti-clockwise direction when looking through the liquid away from the source of light. The contrary rotation is called lasvo (/). The molecular rotation is the specific rotation multiplied by the molecular weight. [a]” indicates that the specific rotation is measured at 20° C. using sodium (D) light. (See Landolt’s “ Optical Rotations of Organic Substances and their Practical Application.”) Optically Active Substance. Solvent. Conditions. Specific Rotation [a]t Cane Sugar or Candy (d), Ci2H22Ojj (Landolt, 1888 ; Pellat, 1901) water c = 4 to 28 t — i4°to3o° C. Woo = + 66-67 - -0095c [4° = H: {i - -00037(/ - 20)} Invert Sugar(/),* C6H1206 = 1 mol. of dextrose + 1 mol. of levulose (Gubbe, 1885) water ^ = 9 to 35 t — 30 to 30° C. H» = “ l9°'7 - *036c [a]? = [a]® + *304(/ - 20) + -ooi65(/— 20)2 Dextrose (d — glucose), c6h12o6 (Parcus and Tollens, 1890; Tollens, 1884) water c — 9'i [«£ = + io5°-2 after 5-5 mins, (a modifica¬ tion) — +52°’5 after 6 hrs. (£ modification) water p — 1 to 18 Hi = +52°‘5 + *025/ l - Glucose, C6H120, (Fischer, 1890) water -*■ II [“£ = -94°‘4 after 7 mins. = — 5i°*4 after 7 hrs. Levulose (/) (fruit sugar), c6H12o6 (Parcus and Tollens, 1890; Ost, 1891) water c — 10 [a]“ = — 104° after 6 mins. = — 920 after 33 mins. water P - 2 to 31 [«£, = -9i0'9 “ 'llP * The molecular weight of cane-sugar is 342 ; which, after conversion to invert sugar, becomes 360. Hence the new concentration of the invert sugar solution is §£where c is the number of grams of cane-sugar in ioo c.cs. of the original solution.