# Densities and Viscosities of Ionic Liquid with Organic Solvents
## 3 Results and Discussion
### Effects of Organic Solvents on The Viscosities of IL  
In general, the Vogel-Fulcher-Tammann (VFT) equation is used to fit the viscosity [50]:  
\[\eta=\eta_{0}\exp[B/(T-T_{0})] \tag{7}\]  
where the unit of the viscosity \(\eta\) is mPa-s; the parameters of \(\eta_{0}\) (mPa-s), \(B\) (K), and \(T_{0}\) (K) are correlated by the measurement viscosity. To check the IL viscosity, Equation (7) is performed to fit the experimental data and the calculated values are compared with the literature data. Table 9 gives the viscosity data and the deviations for the IL viscosities in this work with the literature data [10; 22; 23; 30; 33; 43; 44]. The viscosity of IL is sensitive to the impurities. Due to the different production processes, the impurities in IL are usually different as ionic liquid is purchased from different manufacturers. It is seen that the literature values are larger than the experimental data, but AARD is 1.56%, the maximum relative deviation is 2.38%, illustrating that the divergence between the experimental data with the literature viscosity is acceptable. To the best of our knowledge, there is no more literature data for the comparison. Moreover, the viscosity values of the organic solvents in this work and those in the literature are compared as shown in Figures S10-S12 (in the Supplementary Material). AARD for DMA is 1.4% [20], 2.6% [22], 0.61% [23], 0.63% [26]. AARD for DMF is 1.29% [51], 1.07% [30], 1.77% [33], 1.85% [34], 3.34% [20], 10.96% [35], 6.82% [36], 2.31% [40]. AARD for DMSO is 0.54% [43], 1.96% [44], 1.46% [33], 2.26% [52], 6.67% [35], 2.54% [47], 2.98% [48]. There are some considerable deviations when the experimental viscosities are compared with the literature values, but most of the deviations are in the reasonable range. Then, the experimental viscosities of ionic liquid with the three solvents at atmospheric pressure in the temperature of 303.15 to 338.15 K are conducted and summarized in Tables 10-12. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Compound**} & \multicolumn{4}{c}{**Viscosity/mPa-s**} \\ \cline{2-5}  & **T/K** & **This Work** & **Literature** & **Relative Deviation/\%** \\ \hline
[C\({}_{6}\)mim] [OAc] & 303.15 & 804.52 & 816 [10] & 1.41 \\
308.15 & 529.18 & 537 [10] & 1.46 \\
313.15 & 365.96 & 372 [10] & 1.62 \\
318.15 & 260.01 & 265 [10] & 1.88 \\
323.15 & 190.39 & 194 [10] & 1.86 \\
328.15 & 144.73 & 147 [10] & 1.55 \\
333.15 & 110.31 & 113 [10] & 2.38 \\
338.15 & 88.11 & 90 [10] & 2.10 \\ DMA & 303.15 & 0.88 & 0.856 [22], 0.8792 [23] & \(-\)2.80, 0.09 \\ DMF & 303.15 & 0.77 & 0.766 [30], 0.759 [33] & \(-\)0.52, 1.43 \\ DMSO & 303.15 & 1.81 & 1.843 [44], 1.808 [43] & 1.79, 0.11 \\ \hline \hline \end{tabular} The relative combined standard uncertainty (\(u_{c,r}\)) is \(u_{c,r}(\eta)=0.10\).  
\end{table} 
Table 9: Viscosities of pure compounds at (0.0967 \(\pm\) 0.002 MPa). Figure 3 and Figures S13-S15 (in the Supplementary Material) depict the viscosities of binary mixtures as a function of IL mole fraction at atmospheric pressure. In Figure 3, for the pure IL, when the temperature is 303.15 K, the viscosity is 804.52 mPa-s; the value is 88.11 mPa-s when the temperature is 338.15 K. The temperature has a more influence on IL viscosity.