Fuels：练习题

What is the main constituent of natural gas?

In the fractional distillation of petroleum, which property increases as we move from the top to the bottom of the fractionating column?

A specific fraction from petroleum distillation has a very high viscosity and a very long carbon chain length. In which part of the fractionating column is this fraction most likely collected, and what is its primary use?

Which fraction obtained from the distillation of petroleum is used as a fuel for ships and in home heating systems?

In a fractionating column, as we move from the bottom to the top, which change in physical properties is observed?

Name the main constituent of natural gas and state its chemical formula.

Describe how the boiling point and viscosity of petroleum fractions change as the length of the carbon chain increases.

Identify the petroleum fractions used as (i) fuel for jet aircraft and (ii) a chemical feedstock, and state the physical property used to separate them.

Petroleum is a mixture of hydrocarbons that is separated into useful fractions using the apparatus shown in the diagram.

(a) Explain why the petroleum is heated to approximately \(400^\circ\text{C}\) before it enters the fractionating column and describe the temperature gradient that exists inside the column from bottom to top.

(b) Identify the names of the fractions labeled A (at the highest exit) and H (at the lowest exit) and provide one specific industrial use for each fraction.

(c) Compare the viscosity and flammability of the gasoline fraction with the fuel oil fraction. Explain these differences by referring to the relative size of the molecules and the strength of the intermolecular forces.