Density,
ρ, and speed of sound, u, were
measured for two binary mixtures, 1-ethyl-3-methylimidazolium tetrafluoroborate
(1) + N,N-dimethylformamide (2)
and 1-ethyl-3-methylimidazolium tetrafluoroborate (1) + N,N-dimethylacetamide (2), over the entire range
of compositions at T = 293.15–343.15 K in
5 K intervals using an Anton Paar density and sound velocity analyzer
(DSA 5000). Also excess molar volume, V
m
E, isentropic compressibility, k
s, and isentropic compressibility deviation,
Δk
s, were calculated. For these
two binary mixtures, the V
m
E values were negative in x
1 = 0.1–0.8, they were positive in x
1 ≥ 0.8, and they became more negative with increase
in the temperature from 293.15 to 343.15 K. For both systems, the
most negative V
m
E values were observed in the region of x
1 = 0.5. The V
m
E values were fitted
to the Redlich–Kister polynomial equation. The perturbed chain
statistical associating fluid theory (PC-SAFT) was also employed in
order to correlate the densities of the binary mixtures at the temperature
range of 293.15–343.15 K. The results obtained were in good
agreement with the experimental data.