A biofuel laboratory ferments glucose to produce a 70 mass % ethanol–30 mass % water mixture (Solution E). The research objective is to obtain at least 500 mL of ethanol that is 92 mass % or greater in purity for engine testing. Budget constraints favor energy-efficient methods, and the lab glassware is limited to standard condensers, flasks, temperature probes, and vacuum adapters.
(1) Describe a feasible laboratory procedure that would yield ethanol meeting the required purity specification from Solution E. Outline the essential apparatus and operational steps.
(2) Justify how each critical physical property of ethanol and water exploited in your procedure leads to enrichment of ethanol in the collected fraction.
(3) Predict qualitatively how operating the procedure at a reduced external pressure (for example, 0.60 atm) would influence (i) the temperature range over which the separation occurs and (ii) the total thermal energy consumed, assuming all other variables remain constant.