Inlab, you have chosen to examine the properties of an ideal mixtureof tetrahydr
ID: 678384 • Letter: I
Question
Inlab, you have chosen to examine the properties of an ideal mixtureof tetrahydrofuran (THF, C4H8O) and dimethyl sulfoxide (DMSO,(CH3)2SO). You decide to mix 249 mL ofTHF and 671 mL of DMSO at a temperature of25C and find that the resulting solution has a density of1.031 g/cm3. You measure the vapor pressure ofTHF over the solution to be 47.0 mm Hg. From the CRC Handbook, youfind that at 25C, the densities of pure THF andDMSO are 0.889 g/cm3 and 1.100g/cm3, respectively, and that pure DMSO has a vaporpressure of 0.425 mm Hg at 25C and a normal boiling point of189C. Unfortunately, you were not able to find any data onTHF except that the normal boiling point is66C.
(a) Based on your knowledge of intermolecular interactions,explain why THF and DMSO might bemiscible.
(b) What is the molarity and molality of THF in the DMSOsolution?
(c) What are the mole fractions of each component in thesolution?
(d) What is the total vapor pressure over the solution due toboth the DMSO and THF?
(e) What is the vapor pressure of pure THF at25C?
(f) Using the Clausius-Clapeyron equation for each component,determine the total vapor pressure of the solution if you increasedthe temperature to 45C. Compare this value with the oneyou computed in step (d).
(g) The mole fractions of each component in thevaporphase can be determined using the partial pressures of each gasrelative to the total pressure. What are the mole fractions of bothTHF and DMSO in the vapor phase at 25C and45C?
(h) What does the difference in composition (mole fractions)between the vapor and solution phases say about the difference involatility between THF and DMSO?
(i) Based on what you've found out about how the composition ofthe liquid differs from that of the vapor, explain how youmight go about extracting pure THF from your current mixture. Basedon your findings above, would it be more efficient to do thedistillation at 25C or 45C?
Explanation / Answer
I will give points for partial answers