由实验数据计算氢气的维里系数问题

我们对计算气体物态方程中维里系数的方法作了全面的探讨,提出了如何判定物态方程中项数的四个原则。这四个原则是:(1)用∑v²的大小的变化来判断项的数目应如何选取,其中v为pV的计算值减去其实验值。(2)多项式要满足逐项在数值上减少的级数性质。(3)多项式的末一项大小要与实验误差大小相同。(4)误差v的正负号数目要大致相等。我们建议在计算中要用A₀+B₀+C₀+…=1条件,但不要用A=RT条件。此外还讨论了用压强展开和用密度展开的问题,级数展开式中省去奇数幂次项问题,维里系数的有效位数问题,若干实验数据的修正问题等。我们根据上述原则和建议,重新计算了氢气的维里系数,结果与各原作者所得的有相当的不同。在同一温度用不同实验窒的数据所得的维里系数比各原作者所得的要互相接近些,一般在两倍标准误差内一致。

ON THE CALCULATION OF THE VIRIAL COEFFICIENTS OF HYDROGEN GAS FROM EXPERIMENTAL DATA

We have investigated the methods of calculating the virial coefficients in the equation of state of gases, and proposed four rules for determining the number of terms in the equation of state. These rules are: (1) Use the variation of ∑v² (v = (pV)_cal - (pV)_exp); (2) each succeeding term of the polynomial should be less in numerical value than its preceding term; (3) the last term of the polynomial should be of the same order of magnitude as the experimental error; (4) the residuals v should have nearly equal numbers of positive and negative values.We advise the use of the condition A₀+B₀+C₀+…=1, but not the condition A=RT. We have also investigated whether the expansion is better in increasing powers of pressure or of density, the omission of odd power terms, the number of significant figures in the numerical values of the virial coefficients, and the correction of some experimental data.Based on the above considerations we have recalculated the virial coefficients of hydrogen gas from two different sets of experimental data, with results differing from those of the original authors. The virial coefficients calculated from two different sources agree within twice the standard error, and differ less than those of the original authors.