Solution Properties of Sodium Perfluoroalkanoates. Heats of Solution, Viscosity <i>B</i> Coefficients, and Surface Tensions

Abstract

Abstract The heats of solution, the viscosity B coefficients, and the surface activities of sodium perfluoroalkanoates, F(CF2)nCOONa, n=1–4, 6, 7), in water were measured. The changes in the heat capacity for dissolution in water, ΔCp∞, calculated from the heats of solution at 15, 25, and 35 °C, were positive for the salts, and the ΔCp∞ values increased with an increase in n. The increment in the ΔCp∞ values per CF2 group was 93 J K−1 mol−1. The viscosity B coefficients increased with the chain length at a definite temperature, and the increment in the viscosity B coefficients per CF2 group was 0.119 dm3 mol−1 at 25 °C. Further, the viscosity B coefficients for all the salts decreased with the increase in the temperature between 15 and 35 °C. Traube factors, as obtained from the surface tensions, were found to be 3.0 for the homologs from C2 salt to C7 salt. The results are discussed in comparison with those of sodium alkanoates, H(CH2)nCOONa.