常压下环己烷密度与温度的相关性

以空气和去离子水为标准样,利用振动管密度计测定了常压下环己烷在20~60℃时,几乎每相间1℃密度数据。其中系统温度的控制精度在0.01℃,密度的测量精度为0.000 1 g/cm3。利用3种不同的函数关系,将测量密度与对应温度的数据进行非线性最小二乘法拟合,给出了密度函数的对应参数。对比得出密度与温度间的最优函数关系,用最优函数计算密度的标准误差为0.000 1 g/cm3,符合密度测量精度要求。

Dependence of density of cyclohexane on temperature at atmospheric pressure

The air and the deionized water were considered as standard examples and the densities of cyclohexane were measured over a temperature rang of 20～60 ℃ almost every 1 ℃ with an Anton Paar DMA60 DMA602 vibrating tube densimeter.The precision of the temperature is 0.01 ℃ and the density is 0.000 1 g/cm3.At the same time,the dependences of densities on temperatures are expressed with three different density functions by least-square nonlinear fitting,and the parameters of the density functions are reported.The best density function is given after the comparison among the three functions,and the standard error of estimate of the calculated density from the three-parameter function is 0.000 1 g/cm3,which is consistent with the uncertainty of the measurement of the densities.