(P,ρ,T) properties of 1-octyl-3-methylimidazolium tetrafluoroborate

(p,ρ,T) data of 1-octyl-3-methylimidazolium tetrafluoroborate [OMIM][BF4] over a wide range of temperatures, from 278.15 to 413.15 K, and pressures, p, up to 140 MPa are reported with an estimated ±0.01–0.08 % experimental relative average percent deviation (APD) in the density. The measurements were performed using an Anton Paar DMA HPM vibration tube densimeter. (p,ρ,T) Data for [OMIM][BF4] was fitted and the parameters of the applied equation were determined as a function of pressure and temperature. After a thorough analysis of literature values and validity of the used equation of state, various thermophysical properties, such as isothermal compressibility, isobaric thermal expansibility, differences in isobaric and isochoric heat capacities, thermal pressure coefficient, internal pressure, heat capacities at constant pressure and volume, speed of sound and isentropic exponent at temperatures in the range 278.15–413.15 K and pressures p up to 140 MPa were calculated.