## 4 Discussion
Moreover, with evaporation at room temperature, the use of a 19% v/v isopropanol in n-hexane solution should increase in the concentration of isopropanol as the solution dries, which approximates the concern of differential evaporation that led to the exploration of azeotropes for picture cleaning originally. The room temperature azeotrope composition can also be estimated mathematically. Employing a methodology already described in the literature [22], estimations were conducted for temperature (T\({}_{\text{AZ}}\)), pressure (P\({}_{\text{AZ}}\)), and composition (x\({}_{\text{AZ}}\)) pertaining to the isopropanol and n-hexane system under various conditions. This theoretical calculation relies on empirical data pertinent to the system, including aspects such as enthalpy of vaporization for the respective solvents, vapor pressures of the pure solvents, and a singular dataset of reported azeotropic parameters comprising T\({}_{\text{AZ}}\), P\({}_{\text{AZ}}\), and x\({}_{\text{AZ}}\), and as such, the approach is susceptible to error. Using this estimation procedure from the literature [22], the calculated T\({}_{\text{AZ}}\) and x\({}_{\text{AZ}}\) at various P\({}_{\text{AZ}}\) for the system are depicted in Figures 4 and 5. Additionally, eight values extracted from the literature [16; 17; 18; 19; 20; 21] were integrated into these figures for the purpose of comparing experimentally derived values to the forecasted data. As demonstrated in Figure 4, the analysis yielded a negligible discrepancy between the reported data points of T\({}_{\text{AZ}}\) and P\({}_{\text{AZ}}\) at both the lower and upper extremes of the pressure range. This suggests the calculation from the literature [22] does a good job of approximating the true azeotropic values. At a P\({}_{\text{AZ}}\) of 760 mmHg, which equates to 1 atm and denotes the atmospheric boiling point, the T\({}_{\text{AZ}}\) is situated at 62.7 \({}^{\circ}\)C as shown in Figure 4. Conversely, when the temperature is at ambient levels (approximately 21 \({}^{\circ}\)C), the P\({}_{\text{AZ}}\) undergoes a decrease to 138 mmHg. It is noteworthy that, at room temperature, the value of 138 mmHg exceeds the vapor pressure exhibited by the pure solvents (with isopropanol's vapor pressure at 39 mmHg and n-hexane's at 132 mmHg). This observation aligns with the expectations for a pressure-maximum ('positive') azeotrope. Additionally, our empirical measurements, as depicted in Figure 3, indicate that the vapor pressure of the azeotrope at room temperature approximates the range of 125 to 135 mmHg, which closely corresponds to the computed P\({}_{\text{AZ}}\) at this temperature from Figure 4. \begin{table}
\begin{tabular}{c c c c c} \hline
**T\({}_{\text{AZ}}\) (\({}^{\circ}\)C)** & **P\({}_{\text{AZ}}\) (mmHg)** & **Isopropanol (\% v/v)** & **n-Hexane (\% v/v)** & **Reference** \\ \hline
30.0 & 199.1 & 10.0 & 90.0 & [17] \\
40.0 & 303.0 & 14.1 & 85.9 & [17] \\
43.6 & 380.0 & 13.8 & 86.2 & [18] \\
59.0 & 684.0 & 17.7 & 82.3 & [19] \\
61.6 & 760.0 & 17.9 & 82.1 & [18] \\
61.9 & 760.0 & 18.3 & 81.7 & [20] \\
62.7 & 760.0 & 19.9 & 80.1 & [21] \\
65.0 & 845.0 & 19.2 & 80.8 & [16] \\ \hline \end{tabular}
\end{table} 
Table 2: Reported azeotropic data for the isopropanol and n-hexane system. The extrapolated values of T\({}_{\rm AZ}\) and x\({}_{\rm AZ}\) for the binary system, as visually represented in Figure 5, manifest pronounced variations that are contingent upon the prevailing azeotropic pressure (P\({}_{\rm AZ}\)). The same reported x\({}_{\rm AZ}\) values are depicted in Figure 5 for comparative analysis with the calculated approximations, and it is observed that these literature values are lower than the estimated values by a range of approximately 1-5%. These discrepancies highlight the necessity for empirical determination of the azeotropic composition under ambient temperature conditions. Based on the projected composition in Figure 5, the azeotrope at an ambient temperature of 21 \({}^{\circ}\)C is anticipated to comprise 12.8% v/v isopropanol in the mixture.