Heat capacity and electrical conductivity of aqueous mixtures of [Bmim][BF4] and [Bmim][PF6]

New measurements of molar heat capacity Cp and electrical conductivity σ for aqueous binary systems of 1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim][BF4] and 1-butyl-3-methylimidazolium hexafluorophosphate, [Bmim][PF6] are reported. Heat capacities were measured from 303.2 to 353.2 K with a differential scanning calorimeter having a measurement uncertainty of ±0.015 kJ/(kg K). Electrical conductivities were measured from 293.2 to 353.2 K with a conductivity meter having a measurement uncertainty of ±0.001 (mS/cm). An excess molar heat capacity expression using the Redlich-Kister equation for composition dependence was used to represent the measured Cp of the studied systems. An empirical equation proposed by another researcher was modified to correlate the composition dependence of the measured σ of the investigated systems. The correlations yield satisfactory results. The heat capacities and electrical conductivities of the studied systems presented in this work are, in general, of sufficient accuracy for most engineering-design calculations.