During steam distillation, the rising steam fails to achieve complete saturation with the distillate vapors because_______________?
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Answer: C. Mixing of steam with the material being vaporised is not so intimate as to result in equilibrium
Explanation
Steam distillation involves bubbling steam through high boiling point organic compounds. Incomplete vapor-liquid equilibrium results from finite contact time and poor mixing. Rising steam escapes before achieving complete thermal and mass saturation limits. Steam distillation lowers effective boiling points by utilizing immiscible vapor pressures. Mass transfer rates depend heavily on interfacial contact area and mixing turbulence. Equilibrium requires sufficient residence time for phases to reach saturation.
Extracting essential oils from plant materials frequently utilizes steam distillation units. Poor column internals can lead to vapor bypassing and incomplete steam saturation. Designing efficient distributors ensures better contact between steam and organic phases. Option A is incorrect because operating temperature is determined by mixture vapor pressure. Option B is incorrect because system pressure alone does not dictate saturation efficiency. Option D is incorrect because steam quality does not explain poor mixing kinetics.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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