Question detail
Which of the following best explains why fractional distillation can separate crude oil into distinct fractions?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Alkanes
Question
- A. Crude oil components have identical boiling points but different densities
- B. Crude oil components have different boiling points due to varying chain lengths
- C. Crude oil components have different melting points but similar boiling points
- D. Crude oil components have the same boiling points but different viscosities
Answer
Crude oil components have different boiling points due to varying chain lengths
Explanation
Alkanes of different chain lengths have different boiling points; fractional distillation exploits these differences to separate the mixture.
Common mistake
Misunderstanding Fractional Distillation
Students often think that fractional distillation separates crude oil based solely on boiling points without considering the role of intermolecular forces.
Fractional distillation separates crude oil into fractions based on both boiling points and the strength of intermolecular forces. The formula for separation involves understanding that components with lower boiling points and weaker intermolecular forces vaporize first. For example, lighter fractions like gasoline have lower boiling points than heavier fractions like diesel. Therefore, as the crude oil is heated, the lighter fractions rise and condense at different levels in the fractionating column.
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