Thermophysical properties of 1-ethyl-3-methylimidazolium dicyanamide in a wide range of temperatures and pressures

Abstract

Density ρ(p,T)/kg·m−3 of 1-ethyl-3-methylimidazolium dicyanamide [EMIM][DCA] over a wide range of temperatures at T = (273.15 to 413.15) K and pressures p = (0.101 to 140) MPa is reported. Measurements were performed on Anton Paar DMA 4500 M, DSA 5000 M, DMA HPM vibration tube densimeters with an estimated experimental relative combined average percentage deviation (APD) of Δρ(p,T)/ρ(p,T) = ±(0.01 to 0.08)%. Additionally, at T = (273.15 to 413.15) K and ambient pressure p = 0.101 MPa, dynamic viscosity η(p0,T)/mPa·s measurements were done. They were carried out with uncertainties of Δη/η = ±0.35% and = ±1%, respectively, on an Anton Paar SVM 3000 Stabinger Viscometer and Anton Paar Rheometer MCR 302 installations. Heat capacity cp(p0,T)/J·kg−1·K−1 was determined with an uncertainty Δcp/cp = ±0.1% using a Perkin Elmer Pyris 1 DSC Differential Scanning Calorimeter. The speed of sound u(p0,T)/m·s−1 at T = (278.15 to 343.15) K and ambient pressure p = 0.101 MPa was experimentally investigated using an Anton Paar DSA 5000 M with a standard uncertainty of Δu = ±0.1 m·s−1. Obtained experimental (p,ρ,T) data of [EMIM][DCA] were correlated using an equation of state (EoS). After a thorough analysis of the validity of the constructed EoS, various thermophysical properties were calculated, such as: isothermal compressibility (κT(p,T)/MPa-1), isobaric thermal expansivity (ap(p,T)/K-1), differences in isobaric and isochoric heat capacities ((cp-cv)(p,T)/J·kg-1·K-1), thermal pressure coefficient (γ(p,T)/MPa·K-1), internal pressure (pint(p,T)/MPa), heat capacities at constant pressure (cp(p,T)/J·kg-1·K-1)and volume (cv(p,T)/J·kg-1·K-1), speed of sound (u(p,T)/m×s-1) and isentropic exponent (κs(p,T).