Chemical Engineering Thermodynamics Questions -
Question 1 - Assume solvents A and B are virtually insoluble in each other. Component C is soluble in both.
(a) Use the Scatchard- Hildebrand theory to estimate the distribution coefficient at low concentrations of C given as (mole fraction C in A)/(mole fraction C in B).
(b) If the phase containing A is 0.1 mol% C, estimate the composition of the phase containing B.
(c) If an extractor was designed and constructed, is the distribution coefficient favorable for extraction from B into A? Data:
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Volume (cm3/mole)
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δ(cal/cm3)½
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A
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50
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5.8
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B
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250
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10.4
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C
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100
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9.8
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Question 2 - The bubble point of a liquid mixture of n-butanol and water containing 4 mol% butanol is 92.7oC at 1 bar. At 92.7oC the vapor pressure of pure water is 0.784 bar and that of pure n-butanol is 0.427 bar. Assuming the activity coefficient of water in the 4% butanol solution is near unity, estimate the composition of the vapor and activity coefficient of butanol that gives the correct bubble pressure and compare to the values estimated by UNIFAC.
Question 3 - Water + hexane and water + benzene are immiscible pairs.
(a) The binary system water + benzene boils at 69.4oC and 760 mmHg. What is the activity coefficient of benzene in water if the solubility at this point is xB = 1.6E-4, using only this information and the Antoine coefficients?
(b) What is the vapor composition at the bubble pressure at room temperature (292 K) for a ternary mixture consisting of 1 mole overall of each component if the organic layer is assumed to be an ideal solution?
(c) What is the vapor composition at the bubble pressure at room temperature (292 K) for a ternary mixture consisting of 1 mole overall of each component if the activity coefficients of the organic layer are predicted by UNIFAC?
Question 4 - A 50 wt% (22.5 mol%) solution of ethylene glycol + water freezes at about 240 K.
(a) What freezing temperature would be predicted by assuming that ethylene glycol and water form an ideal solution? The freezing occurs by formation of water crystals.
(b) Does your calculation indicate that the system has positive or negative deviations from Raoult's law? Why?