Examkin

Question

Difficulty: EasyIndustrial Applications of Separation Methods

During the industrial separation of liquified air by fractional distillation, nitrogen gas is collected before oxygen at the top of the fractionating column. Which of the following explains why nitrogen is collected first?

  1. Nitrogen has a lower boiling point than oxygenAnswer
  2. B
    Nitrogen has a higher boiling point than oxygen
  3. C
    Nitrogen is more dense than liquid oxygen
  4. D
    Nitrogen reacts with liquid oxygen to form a volatile oxide

Answer

Nitrogen is collected first because it has a lower boiling point than oxygen.
Nitrogen has a lower boiling point (-196 °C) than oxygen (-183 °C). In fractional distillation, liquid mixtures are separated according to boiling point, so the component with the lowest boiling point vaporizes first and distills at the top of the column.

Step-by-Step Solution

1
Identify the principle governing industrial fractional distillation of liquid air.
Components are separated according to their boiling points, with the substance having the lowest boiling point vaporizing and distilling over first.
Fractional distillation depends on boiling point differences to separate liquid mixtures.
2
Compare the boiling points of nitrogen and oxygen.
Nitrogen has a boiling point of -196 °C (77 K) while oxygen has a boiling point of -183 °C (90 K).
Because -196 °C is lower than -183 °C, nitrogen vaporizes first at the lower temperature.

Key Concept

Fractional distillation of liquid air based on boiling points
Estimated Time:45s
Rate this question

Topics

Industrial Applications of Separation Methods