Surface tension and 0.1 MPa density of 1-alkyl-3-methylimidazolium tetrafluoroborates in a homologous series perspective

Abstract

Experimental data over the temperature range from (263 to 365)K are presented on the 0.1MPa density and air–liquid surface tension for 1-Cn-3-methylimidazolium tetrafluoroborates with n=3,5,7,9,10 and 12, still poorly or even not studied in these respects at all. The reported density data were obtained using a single-sinker buoyancy method with an estimated combined expanded uncertainty at 0.95 confidence level Uc not exceeding 0.6kg·m−3 (6·10-4ϱ). The surface tension data were obtained by the Wilhelmy plate method with Uc from 0.04 to 0.12mN·m−1 for n=3 and n=12, respectively, and by du Noüy ring method with Uc from 0.17 to 0.8mN·m−1. The Krűss K100 Mk2 tensiometer was used to determine the buoyancy and surface tension forces. The new data allowed to identify the most credible density and surface tension values for 1-Cn-3-methylimidazolium tetrafluoroborates with n=2,4,6, and 8. Empirical models rooted in group contribution and parachor concept are reported, generating recommended values for the 0.1MPa density and the surface tension for members of the studied homologous series. The worst-case error of the recommended values of the density and surface tension are estimated to 0.1% and 0.3mN·m−1, respectively.