why is it possible to use fractional distillation to separate hydrocarbons in petroleum?
Is it because the temperature is high enough to separate them?
petroleum has many different compounds all with different chain lengths so if it is heated the smaller chain length molecules rise and the heavier stay at the bottom due to density differences
Is petroleum crude oil?
http://science.howstuffworks.com/oil-refining1.htm
thanks :)
Your proposed answer is not adequate. The proposed answer by DAS won't get it although petroleum does contain many different hydrocarbons. As their chain length increases, the boiling point also increases; therefore, each of the components boil at a different temperature. In fractional distillation, the mixture is heated at a low temperature until all of the lowest boiling material is carried out of the pot, up the distilling flask to the side arm, and into the condenser where it is returned to the liquid state and drips into a container. Then the temperature of the pot is increased until the next fraction is reached, a separate container is placed at the end of the condenser to catch that fraction, and the process continues until all of the components have been separated. There are a number of variations on the apparatus but density of the materials don't enter into it. The boiling points are the key ingredient. Not every single component can be separated if their boiling points are too close together.Here is a good discussion as well as a picture of the apparatus.
http://en.wikipedia.org/wiki/Fractional_distillation
Ohhh, before I didn't know that petroleum is crude oil, I have a diagram in my textbook, thanks!
Fractional distillation is used to separate hydrocarbons in petroleum because of their different boiling points. Each hydrocarbon has a unique boiling point, and by heating the mixture in a fractional distillation column, it is possible to separate the components based on their boiling points.
When petroleum is heated, the mixture evaporates, and the resulting vapors rise through the fractional distillation column. The column is designed with a temperature gradient, meaning that the temperature decreases from the bottom to the top. As the vapors rise, they encounter different temperatures within the column.
The hydrocarbons with lower boiling points, such as gasoline and other volatile components, have lower boiling points and evaporate first as they reach temperatures below their boiling points. These components become vapors and rise up the column.
On the other hand, hydrocarbons with higher boiling points, such as diesel, kerosene, and heavier components like lubricating oils, have higher boiling points. They do not evaporate until they reach temperatures closer to or above their boiling points. These components remain in the liquid state and are collected at various points in the column.
By strategically collecting the condensed fractions at different levels of the column, it is possible to obtain the desired hydrocarbon products at various boiling point ranges. This process allows for the separation of hydrocarbons based on their boiling points, making fractional distillation an effective method for refining petroleum.