heyy
im doing as too and i have some work i can copy an paste in(?) its book on petroleum an alkanes- cracking, fractional distillation and combustion. its quite detailed and i found it intrestingg... ill do a bit now an if its the right stuff your looking for ill do more...k?
Topic 1.6
PETROLEUM AND ALKANES
Fractional Distillation
Cracking
Combustion
"
CRUDE OIL
Introduction
The vast majority of carbon-containing compounds in widespread use have been made from crude oil. Crude oil is also known as petroleum.
Crude oil is a mixture of hydrocarbons. A hydrocarbon is a substance containing carbon and hydrogen only. Most of the hydrocarbons in crude oil are alkanes. Alkanes are hydrocarbons containing only single bonds between the carbon atoms.
Each of the hydrocarbons present in crude oil has a slightly different use. Mixed together they are of no use at all. It is necessary, therefore, to separate them before they can be used productively. Crude oil is separated into its different components by a process called fractional distillation.
The products of fractional distillation are often converted into other, even more useful hydrocarbons by a process called cracking.
Fractional distillation
The different hydrocarbons in crude oil have different boiling points. This is because the chain length varies. The greater the number of carbon atoms in the chain, the longer the chain length. This results in more Van der Waal’s forces acting between the molecules and a greater intermolecular attraction. Thus more energy is needed to separate the molecules and the boiling point is higher. It is the difference in boiling points of the different hydrocarbons in crude oil which is used to separate them from each other.
The crude oil is passed into a tall tower called a fractionating column. This is very hot near the base but much cooler near the top. When the crude oil is passed into the tower, near the bottom, most of the mixture boils and starts to rise up the tower. As they rise up the tower, they start to cool down and will gradually condense back into liquid form. They are then tapped off. The larger hydrocarbons, with higher boiling points, will condense first and be tapped off near the base of the column. The smaller hydrocarbons, with smaller boiling points, will condense later and be tapped off near the top of the column. Thus the separation is achieved. Not that the process involves breaking intermolecular forces only; the molecules themselves are unaffected by this process.
This process does not actually separate the crude oil mixture into pure hydrocarbon components, but into mixtures called fractions. Fractions are mixtures of hydrocarbons with similar boiling points. In many cases these fractions can be used directly, but sometimes further separation is required into purer components.
The following page shows a diagram of a typical fractionating column, and a table showing the most important fractions and their main uses: "
yeh well its quit elong.....and theres a lot more...it has diagrrams an all sorts
so let me know
hope it helps
chocs
