In this study, measurements regarding the density and speed of sound for binary liquid mixtures of the 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆]) ionic liquid (+ methanol, or + acetonitrile, or + tetrahydrofuran, or + formamide, or + N,N-dimethylformamide, or + dimethylsulfoxide) were carried out as a function of the composition at temperatures between 288.15 and 313.15 K and atmospheric pressure. Experimental results allowed us to calculate the excess molar volume, , and excess isentropic compressibility, , which were fit to a Myers–Scott-type polynomial. The results for the studied systems suggest that structural effects and chemical interactions must predominate over other possible effects, except for the system containing formamide in which physical effects may also be more important.

中文翻译：

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分子溶剂对1-丁基-3-甲基咪唑六氟磷酸盐二元混合物体积和声学性质的实验测量

在这项研究中，关于六氟磷酸1-丁基-3-甲基咪唑鎓（[BMIM] [PF ₆ ]）离子液体（+甲醇或+乙腈或+四氢呋喃）的二元液体混合物的声速和密度的测量在288.15和313.15 K之间的温度和大气压下，根据组成进行+（甲酰胺，或+ N，N-二甲基甲酰胺，或+二甲基亚砜）。实验结果使我们能够计算出过量的摩尔体积和过量的等熵压缩率，，适用于Myers-Scott型多项式。对于所研究体系的结果表明，除了含甲酰胺的体系（在该体系中物理效应也可能更为重要）以外，结构效应和化学相互作用必须优于其他可能的效应。