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Difficulty: EasyAlkanes: Properties, Reactions, and Petroleum Refining

Arrange the following crude oil (petroleum) fractions in order of increasing boiling point range, starting from the fraction with the lowest boiling point to the one with the highest boiling point.

  1. 1Refinery gas
  2. 2Petrol (Gasoline)
  3. 3Kerosene (Paraffin)
  4. 4Diesel oil (Gas oil)

Answer

The correct order from lowest to highest boiling point range is Refinery gas, followed by Petrol (Gasoline), Kerosene (Paraffin), and Diesel oil (Gas oil).
In the fractional distillation of petroleum, fractions condense and exit the fractionating column at different levels depending on their boiling point ranges. Smaller alkane molecules have lower molecular masses, weaker intermolecular forces, and lower boiling points. Thus, Refinery gas (C1−C4C_1-C_4) has the lowest boiling point, followed by Petrol (C5−C10C_5-C_{10}), Kerosene (C10−C16C_{10}-C_{16}), and Diesel oil (C14−C20C_{14}-C_{20}) with the highest boiling point among the listed options.

Step-by-Step Solution

1
Determine the relationship between carbon chain length and boiling point in alkane fractions.
Smaller hydrocarbon molecules have weaker intermolecular van der Waals forces and therefore lower boiling points.
Boiling point increases as the number of carbon atoms per molecule increases.
2
Identify the carbon chain lengths for each given fraction.
Refinery gas (C1−C4C_1-C_4), Petrol (C5−C10C_5-C_{10}), Kerosene (C10−C16C_{10}-C_{16}), and Diesel oil (C14−C20C_{14}-C_{20}).
Fractional distillation separates crude oil based on boiling point ranges governed by molecular sizes.
3
Arrange the fractions from smallest carbon number to largest carbon number.
Refinery gas →\rightarrow Petrol →\rightarrow Kerosene →\rightarrow Diesel oil.
This sequence directly corresponds to increasing boiling point range.

Key Concept

Fractional Distillation and Boiling Point Trends of Petroleum Fractions
Estimated Time:45s
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Topics

Alkanes: Properties, Reactions, and Petroleum Refining

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