Useful Products from Organic Sources

ORGANIC CHEMISTRY

How coal formed

Over millions of years, due to high temperatures and pressure…

…the trees became fossilized, forming coal.

Millions of years ago trees died and fell to the bottom of swamps.

Over time they became covered by mud and rock.

How oil and natural gas formed

Crude oil

• Crude oil is a mixturemixture. It contains hundreds of different compounds. Some are small but most are large.

• Nearly all of these compounds contain carbon and hydrogen only. only.

• They are called hydrocarbons.• Also some other compounds contain small amounts of Also some other compounds contain small amounts of

N and S. Why?N and S. Why?

Hydrocarbons are molecules that contain carbon and hydrogen onlyonly.

How oil and natural gas formed

Q1 Explain why oil contains carbon and hydrogen.

Q2 Explain where the energy in oil originated.

The importance of oil

• The hydrocarbons in crude oil are essential to our way of life

• We use them as fuels for most forms of transport.

• We also use them as raw materials from which a

HUGE range of useful everyday substances are made .. Such as…………..make a list!

• Crude oil is a mixture of hydrocarbons with a VERY wide range of sizes.

• Crude oil itself has no uses because its properties are

not definite. • To make crude oil into useful substances we have to

separate the mixture into molecules of similar size.• This is done in an oil refineryoil refinery in a process called

fractional distillation.• The physical property used to separate the fractions is

boiling point.

Making oil useful

Fractional Distillation

Can you predict and explain where the fractions are obtained from the fractionating tower?

Fraction Boiling Range

(oC)

Kerosene 150 - 240

Diesel 220 – 275

Petrol 40 - 175

Bitumen >350

Fuel gas Below 40

Lubricating oil 250-350

cool

hot

Fuel gas

Petroleum

Kerosene

Diesel

Lub. Oil

Bitumen

Fractional Distillation

Why do these fractions condense over a boiling range?

Fraction Boiling Range (oC)

Fuel gas Below 40

Petrol 40 - 175

Kerosene 150 - 240

Diesel 220 – 275

Lubricating oil 250-350

Bitumen >350

cool

hot

Fuel gas

Petroleum

Kerosene

Diesel

Lub. Oil

Bitumen

Fractional Distillation

Fuel gas

Petrol / gasoline

Naphtha

Paraffin / Kerosine

Diesel fuel

Fuel and lubricating oil

Bitumen

Burned in the refinery to fuel the distillation process, sold as LPG, purified and sold as bottled camping gas

Fuel for cars and motorcycles, also used to make chemicals.

Used to make chemicals used everwhere.

Fuel for greenhouse heaters and jet engines, manufacture of chemicals.

Fuel for lorries, trains.

Fuel for the heating systems of large buildings, fuel for ships, lubricating oil.

Roofing, and road surfaces.

Uses of each fraction

Why are the fractions useful?

Similarities between crude oil and its fractions:

Differences between crude oil and its fractions:

The boiling points of molecules

In general, the bigger the molecule the higher the boiling point.

0

50

100

150

200

250

300

350

0 5 10 15 20

No. Carbon atoms

B.Pt

(oC)

Here are the boiling ranges of some fractions obtained from distillation of petroleum.1. Using the previous graph, estimate the size range of the molecules present in each fraction.

Fraction Boiling Range

(oC)

Number of carbons

Fuel gas Below 40

Petrol 40 - 175

Kerosine 150 - 240

Diesel 220 - 275

1-5

5-10

9-14

13-17

What is crude oil?

• Crude oil is a mixture of different sized hydrocarbons. The exact composition depends upon where the oil comes from but typically it contains a lot of big molecules. (Why is this not good?)

Fuel gas PetrolNaphtha KerosineDiesel Fuel Oil and bitumen

Small molecules

Medium molecules

Big molecules

Which is a correct statement about crude oil?

A. A mixture of carbohydrates.

B. Formed by the decay of dead sea creatures.

C. Consist of a mixture of very large molecules.

D. Is purified in an oil rig.

Which is a correct statement about fractionaldistillation?

A. Oil is separated into fractions with the same size molecule.

B. Oil is separated into fractions with the same density.

C. Oil is separated into fractions with similar size molecules.

D. Oil is separated into alkanes and alkenes.

Which is a correct order for these fractions working down from the top of the column?

A. Fuel gas, kerosene, petrol, diesel, bitumen.

B. Fuel gas, diesel, kerosene, petrol, bitumen.

C. Fuel gas, petrol, diesel, kerosene, bitumen.

D. Fuel gas, petrol, kerosene, diesel, bitumen.