Separating Oil into Fractions & Cracking Hydrocarbons 10.02 & 10.03 p170-173

• Explain how crude oil can be separated through fractional distillation (CC17)

• Video

• http://www.youtube.com/watch?v=26AN1LfbUPc

•A mixture of of many different chemical compounds. Separated by fractional distillation

•Nearly all the compounds in crude oil are hydrocarbons. Hydrocarbons are compounds which contain the elements hydrogen and carbon.

•Most of the hydrocarbons in crude oil are alkanes.•These alkanes all end in –ane e.g. methane

•The general formula for these compounds is:

CnH2n + 2

How does Hydrogen and Carbon bond together?

• Covalent bonds=Kovalenta bindningar

• Covalent bonds=share electrons

• Hydrogen has only 1 electron, in its outer shell

• Carbon has 6 electrons, 2 in its first shell and 4 in its outer shell

Bonding

• How many electrons does an atom need in its outer shell to become stable=happy?

How many electrons does an atom need in its outer shell to become stable=happy?

• Answer=8 electrons. Except Hydrogen that is happy with 2 electrons in its outer shell.

• This means that one carbon atom will share electrons with 4 Hydrogen atoms.

• The Carbon borrows one atom from each Hydrogen and ends up with thinking that it has 8 electrons in its outer shell=stable=happy;).

• Each Hydrogen borrows one electron each from the Carbon, thinking that it has 2 electrons in its outer shell=stable=happy.

Hydrocarbons

One Carbon atom can also bond together with another Carbon atom, they then share 4 electrons between them but need 2 Hydrogen atoms each too in order to think that they have a full outer shell.

Crude Oil

• Crude oil cannot be used for anything useful because of all the different sizes of hydrocarbons inside of it.

See chapter 2.05 p34 in your Chemistry book for more about covalent bonding.

Alkane Formula Chemical Structure

Methane CH4

Ethane

Propane

Butane

Saturated hydrocarbons - they contain as many hydrogen atoms as possible

Make a poster about Fractional Distillation and how it is used to separate crude oil. Include the following information:

•Labeled picture of the column

•Temperature labels (high to low)

•Names of the products removed at each fraction

•Clear explanation of how the mixture is separated using all the keywords below:

Heating Evaporates Cools Condenses

Mixture High Boiling Point Low Boiling Point

Hotter Cooler Vapour Hydrocarbon

1. How does the length of the hydrocarbon affect the boiling point and viscosity of the hydrocarbon?

2. A hydrocarbon catches fire easily. Is it likely to have long or short chains? Why?

3. ‘Light’ crude oil is pale and runny, often produced in Nigeria and Saudi Arabia. ‘Heavy’ crude oil is dark and thick, often produced in Venezuela.

Why is ‘light’ crude oil likely to cost more than ‘heavy’ crude?

You have 4 minutes to answer all the questions giving as much detail as you can: