二元体系C_6H_5CH_3-DMF在293.15K时的体积性质

Volumetric Properties of Binary System C_6H_5CH_3-DMF at 293.15 K

利用Anton Paar DMA4500振动管密度计测量了293．15K时二元体系甲苯-N，N-二甲基甲酰胺（C6H5CH3-DMF）在C6H5CH3（摩尔分数0～1）中的溶液密度，利用最小二乘法关联了溶液密度与组成的函数关系，关联精度为±0．005kg／m^3。通过密度数据分别计算了二元体系中C6H5CH3和DMF的表观摩尔体积，并利用非线性最小二乘拟合法，分别拟合得到了优化的C6H5CH3和DMF的表观摩尔体积和摩尔分数的函数关系，以及C6H5CH3和DMF的表观摩尔体积和质量分数的函数关系．通过对函数关系的极限运算得到了C6H5CH3和DMF的极限偏摩尔体积、标准偏摩尔体积和摩尔体积．还计算了不同组分下体系的超额摩尔体积，数据可用四参数Redlich—Kister方程关联拟合得到方程系数．计算关联了C6H5CH3和DMF的超额偏摩尔体积与摩尔分数的关系．由三参数多项式极限法得到组分的极限超额偏摩尔体积值与Redlich—Kister系数法得到的值在误差范围内一致．

The densities of binary solution C6H5CH3-DMF（ toluene-N, N-dimethylformamide） at 293.15 K were measured by use of the Anton Paar 4500 vibrating-tube densimeter and the dependence of density on molar fraction was fitted by the least-square method with the standard deviation 0. 005 kg/m^3, the molar fractions of toluene for the binary solution is from 0 to 1. The apparent molar volumes of C6H5CH3 and DMF in the binary system C6H5CH3-DMF were separately calculated from the density data, and the optimized dependences between apparent molar volumes and molar fractions and mass fractions were also determined respectively by the nonlinear least-square regression, and further more, the limiting partial molar volumes, the standard partial molar volumes and the molar volumes of C6H5CH3 and DMF were also obtained from the functions limits. At the same time, the excess molar volumes for the binary solution were calculated and were fitted by the fourth-order Redlich-Kister equation well, so the Redlich-Kister coefficients and the excess molar volume extremum were obtained. Furthermore, the excess partial molar volumes of C6H5CH3 and DMF were calculated and the dependences of the excess partial molar volumes on molar fractions of C6H5CH3 were fitted with the three-parameter polynomial. The limiting excess partial molar volumes of C6H5CH3 and DMF were also obtained from the polynomials limits as well as from the Redlich-Kister equation coefficients.