need help with ochem lab questions, please explain. thanks During the fermentati
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need help with ochem lab questions, please explain. thanks
During the fermentation reaction it is important to prevent air from entering the reaction chamber. Why? Compare and contrast a fractional distillation to a simple distillation. Support your explanation with the ignition tests' data. What is an azeotrope? Does it limit our ethanol purity even when we are doing a fractional distillation? Explain. What is the percentage of ethanol purity in your fractional distillate? Did you get "pure" ethanol? If not, why. Consider the chemicals used for this experiment. What realistic hazards are present? What safety procedures are necessary beyond wearing goggles and gloves? What was green about this experiment and what was not (refer to the related principles of green chemistry in your answer for this question)?Explanation / Answer
1. Fermentation is an anaerobic process. In this process, sugar is converted to ethanol in tha absence of air. If air enters the reaction chamber the oxidation of sugar would proceed to completion yielding CO2 and H2O instead of ethanol.
2. In distillation, the liquid is heated and is set to boiling when the vapor pressure of the liquid becomes equal to the atmospheric pressure. THis technique is employed in separation of many pure liquids. But some liquids like water ethanol mixture doesnot behave in this way and they form azeotrope, which makes the separation of pure ethanol difficult by ordinary simple distillation. Hence, fractional distillation is employed to ensure that the vapors from the distillation pots are recondensed and revaporized several times so that it can lead tot he separation of pure ethanol.
3. Ethanol boils at 78.4 °C, water boils at 100 °C whereas the azeotropic mixture of ethanol + water boils at 78.2 °C. The mixture of ethanol and water boils as if it were a pure liquid with a definite boiling point, and the vapour composition is exactly the same as the liquid. This mixture is termed as azeotropic mixture.
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