During fractional distillation, the crude oil is heated at the base of the column until vapour is formed. Say whether the vapour contains more or less than the more volatile hydrocarbons.
Then, explain how this process is used to separate the fractions of crude oil.
Vapour contains more? Not sure why and how to explain.
Heating and mixing?
For any help given, thanks in advance!
http://en.wikipedia.org/wiki/Fractional_distillation
During fractional distillation, the vapour that is formed contains more of the more volatile hydrocarbons. This is because the more volatile hydrocarbons have lower boiling points, and they vaporize more easily when the crude oil is heated.
To explain how the process of fractional distillation is used to separate the fractions of crude oil, let's start with the setup. Crude oil is heated in a tall vertical column, known as a fractionating column. The column has a temperature gradient, meaning that the temperature decreases as you go upward.
When the crude oil is heated at the base of the column, it starts to evaporate, forming a mixture of vapors that rise up through the column. As the vapors rise, they encounter different temperature zones within the column. This temperature gradient causes the vapors to condense at different levels based on their boiling points.
The hydrocarbons with lower boiling points, such as propane and butane, have higher vapor pressures and condense at the lower sections of the column, where the temperature is higher. These condensed hydrocarbons are collected as the first fractions of the distillation process.
As you move up the column, the temperature gradually decreases. This allows the hydrocarbons with higher boiling points, such as gasoline, kerosene, and diesel, to condense and collect at different levels. This separation occurs because each fraction of hydrocarbons has a specific boiling point range.
The fractions collected at different levels of the column are then drawn off and further processed to remove impurities and obtain pure products. For example, gasoline is refined from the fraction collected in the lower part of the column, while heavier fractions like diesel and lubricating oil are obtained from the higher portions.
Overall, the fractional distillation process separates crude oil into different fractions based on their boiling points, utilizing a temperature gradient in the fractionating column. The more volatile hydrocarbons vaporize and condense at lower temperatures, while the less volatile ones condense at higher temperatures, allowing for the separation of various products.