Chemistry 245- 061
Biosynthesis of Ethanol from Sucrose
Ethanol can be created using two methods: acid catalysed hydration of ethylene and through fermentation of sucrose. The purpose of this experiment was to use fermentation to produce ethanol from commercial sucrose (store-bought sugar), using fractional distillation of the fermented solution. The percent ethanol in the fermented solution was then calculated. Mechanism:
Mass of conical vial
Mass of conical vial with distillate
Mass of distillate (mass of vial-mass of vial with distillate) 11.17 g – 10.36 g = 0.81 g
Volume of distillate using automatic pipet
Density of distillate (mass of distillate/volume of distillate)
Percent composition by weight of ethanol using table on page 006 ~90%
Percent composition by volume of ethanol using table on page 006 ~93.3%
1 sucrose→4 ethanol
100 % weight and volume percent EtOH
(from table): 93.3% EtOH by volume.
The percent yield of ethanol from sucrose was successfully high, at 93.3 %. The final mass of the distillate obtained after fermentation and the fractional distillation process was 0.81g. The distillate was collected when the temperature reached approximately 50-70°C. The amount of ethanol that should have been produced was 13.66 ml, had the entire distillate (over 100 ml) been distilled fractionally . The density of the distillate obtained was 0.81 g/mL; therefore, the percent ethanol by weight was approximately 90%. The distillate contained mostly ethanol, but also contained water because due to the azeotropic mixture water and ethanol mix to produce, consisting of 95% ethanol and 5% water by weight. This experiment was a success due to the high percent yield of ethanol from the fermentation of sugar.
Errors introduced to this lab consisted of using unclean glassware...
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