TOPIC 8 Earth And Atmospheric Science
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Number of carbons in a carbon chain and their names
1 meth- 2 Ethel- 3 prop- 4 But- 5 pent- 6 hex-
Homologous series
Group of compounds with the same functional group and so react in similar ways
Functional group
Group of atoms that determine how a compound generally reacts.
What do you do if there’s more than one identical functional group?
Use di- for two Tri- for 3 Tetra for 4
Crude oil
A mixture of substances (mostly hydrocarbons of different lengths) which are separated through fractional distillation.
Where does fractional distillation take place?
In a fractionating column with a temperature gradient (coolest at top, hottest at bottom).
Where do larger hydrocarbons end up?
At the bottom of the fractionating column due to having higher bp’s.
Where do shorter hydrocarbons end up?
At the top of the fractionating column due to having lower bps.
What stops the liquid from remixing in the fractionating column?
Bubble caps make sure each fraction is separated into a mixture of hydrocarbons containing similar bps.
Saturated hydrocarbon
Hydrocarbons containing only single bonds.
Unsaturated hydrocarbons
Hydrocarbons containing double/triple bonds between carbon atoms.
Number of carbons in carbon chain in gas and its use
1-3 Used for heating and cooking
Number of carbon chains in petrol and its use
8 Used for fuel in cars
Number of carbons in chain for kerosene and its use.
15 It’s used for aircraft fuel.
Number of carbons in diesel and its use
20 Used for fuel in large vehicles
Number of carbons in chain in fuel oil and its use
40 It’s used as fuel in large ships and in power stations.
Number of carbons in chain for bitumen and its use
70+ Used in tarmac
Viscosity
Resistance of tendency to flow
Characteristics of longchain hydrocarbons
Viscous Low ease of ignition and volatility High bp
Volatility
Tendency of a substance to vaporise
Characteristics of short chain hydrocarbons
Low viscosity V flammable and volatile Low bp
Cracking
Splitting up of low in demand longchain hydrocarbons to create shorter chain hydrocarbons that are high in demand. It’s a form of thermal decomposition.
Give an example of cracking
Decane»_space; octane + ethene
How do you crack hydrocarbons in a lab
Vaporised hydrocarbons are passed over a powdered catalyst. Much energy is needed to break the bonds so cracking is carried out at 400—700 degrees Celsius .