Suppose you are doing a batch steam distillation of a mixture that has two volatile organic compounds, n-octane and \(n\)-decane, that are immiscible in water plus a nonvolatile organic compound that is also immiscible in water. The total pressure is \(0.98 \mathrm{bar}\), and the mole fractions of n-octane and n-decane are 0.22 and 0.14 , respectively, in the organic liquid. If the \(\mathrm{n}\)-octane and \(\mathrm{n}\)-decane follow Raoult's law in the organic liquid, what is the temperature of the still pot, and what are the mole fractions of n-octane, n-decane, and water in the vapor?

Data: Green and Perry (2008, Table 2-8) VP in Pa, T in K:

\(\ln (\mathrm{VP})=\mathrm{C} 1+\mathrm{C} 2 / \mathrm{T}+\mathrm{C} 3 \ln \mathrm{T}+\mathrm{C} 4 \mathrm{~T}^{\mathrm{C} 5}\)

decane: \(\mathrm{C} 1=112.73, \mathrm{C} 2=-9749.6, \mathrm{C} 3=-13.245, \mathrm{C} 4=7.1266 \mathrm{E}-06, \mathrm{C} 5\)

\(=2\)

octane: \(\mathrm{C} 1=96.084, \mathrm{C} 2=-7900.2, \mathrm{C} 3=-11.003, \mathrm{C} 4=7.1802 \mathrm{E}-06, \mathrm{C} 5\)

\(=2\)

water: \(\mathrm{C} 1=73.649, \mathrm{C} 2=-7258.2, \mathrm{C} 3=-7.3037, \mathrm{C} 4=4.1653 \mathrm{E}-06, \mathrm{C} 5\) \(=2\)

Transcribed Image Text:

TABLE 2-8. Vapor-liquid equilibrium data for methanol water (p = 1 atm) (mol %) Methanol Liquid Methanol Vapor Temp., C 0 0 100 2.0 13.4 96.4 4.0 23.0 93.5 6.0 30.4 91.2 8.0 36.5 89.3 10.0 41.8 87.7 15.0 51.7 84.4 20.0 57.9 81.7 30.0 66.5 78.0 40.0 72.9 75.3 50.0 77.9 73.1 60.0 82.5 71.2 70.0 87.0 69.3 80.0 91.5 67.6 90.0 95.8 66.0 95.0 97.9 65.0 100.0 100.0 64.5