Electric Moments of the Methyl and Ethyl Alcohol Molecules

摘要

The dielectric constant of methyl alcohol vapor has been measured at 14 temperatures between 25.0deg;C and 206.0deg;C. At each temperature measurements were made at an average of 23 different pressures ranging from zero to near saturation. The slope, obtained by least squares, of the resulting (Kmdash;1)/(K+2)versuspressure curve gives one point on the Debye line. The 14 such points fall accurately on a straight line whose equation as obtained by least squares, and after making proper allowance for probable errors of calibration, is:lsqb;lpar;Kminus;1rpar;sol;lpar;Kplus;2rpar;rsqb;RTsol;pprime;equals;lpar;7.72plusmn;0.15rpar;plus;lpar;17,730plusmn;71rpar;sol;T. Using recently established values of the Boltzmann gas constant and Avogadro's number, this yields a value (1.706plusmn;0.005)times;10mdash;18e.s.u. for the electric moment of the methyl alcohol molecule. Taking the sum of the electronic and atomic polarization as 8.6 leads to an electric moment of (1.688plusmn;0.006)times;10mdash;18. The mean (1.698plusmn;0.005)times;10mdash;18is taken as the electric moment of the methyl alcohol molecule. Data on ethyl alcohol previously published by Knowles have been recalculated, using a least squares treatment throughout, and making a minor correction to the value used for the absolute zero of temperature. The data conform to the equationlsqb;lpar;Kminus;1rpar;sol;lpar;Kplus;2rpar;rsqb;RTsol;pprime;equals;lpar;13.06plusmn;0.20rpar;plus;lpar;17,725plusmn;87rpar;sol;T, wherein probable errors of calibration have again been allowed for. This yields a moment (1.706plusmn;0.006)times;10mdash;18. Taking the sum of electronic and atomic polarization as 13.6 leads to a moment (1.696plusmn;0.008)times;10mdash;18. The mean (1.702plusmn;0.007)times;10mdash;18is taken as the electric moment of the ethyl alcohol molecule.