Thermophysical properties, namely, density (ρ) and speed of sound (u) of binary mixtures of 1-butyl-3-methylimidazolium methyl sulphate [BMIM][MeSO₄] ionic liquid (IL), with acetic acid or propionic acid have been measured in the mole fraction range from 0.1 to 1.0 at temperature ranging from 293.15 to 313.15 K at a 5 K interval, under atmospheric pressure of 101 kPa. From these measured values, the derived thermodynamic parameters, such as, isentropic compressibility (κ_s), deviation in isentropic compressibility (Δκ_s), excess molar volume (V) and intermolecular free length (L_f) have been calculated. It is observed that V and Δκ_s decrease with increasing the temperature. Furthermore, these values are negative in the whole range of binary compositions. The measured data and variations in derived thermodynamic values suggest that significant interactions occur when the IL forms a binary mixture with carboxylic acids. These derived thermodynamic parameters (V, L_f and Δκ_s) are correlated byusing the Redlich-Kister polynomial equation to generate binary factors and standard errors.

中文翻译：

---

[BMIM] [MeSO4]离子液体与羧酸的二元体系的热物理和热力学性质

已经研究了1-丁基-3-甲基咪唑硫酸甲酯[BMIM] [MeSO ₄ ]离子液体（IL）与乙酸或丙酸的二元混合物的热物理性质，即密度（ρ）和声速（u）。在101 kPa的大气压下，以293.15至313.15 K的温度在5 K的间隔内以0.1至1.0的摩尔分数测量。从这些测量值，导出热力学参数，诸如，等熵压缩（κ_小号），偏差等熵压缩（Δκ_小号），过量摩尔体积（V ）和分子间的自由长度（L _˚F）已经被算出。据存在V和Δκ_小号随着温度升高而降低。此外，这些值在二元组成的整个范围内均为负值。实测数据和推导的热力学值的变化表明，当IL与羧酸形成二元混合物时，会发生明显的相互作用。这些衍生的热力学参数（V ，L _˚F和Δκ_小号）是相关的byusing瑞德利奇-Kister多项式方程来产生二进制因子和标准误差。