Why are the hydrocarbons in petrol volatile?
1 Answer
Oct 29, 2016
All hydrocarbons are volatile, but some hydrocarbons are more volatile than others.
Explanation:
Petrol (gasoline) is a mixture of alkanes, cycloalkanes, and alkenes with between 4 and 12 carbon atoms per molecule.
The boiling points of butane, pentane, and hexane are, respectively, 0 °C, 36 °C, and 69 °C.
They are the ones you smell at ordinary temperatures.
Even dodecane has a vapour pressure of 18 Pa at 25 °C.
This may seem low, but its boiling point is 214 °C, so it is easily converted to a gas in an internal combustion engine.
