C5 - Other Products Of Crude Oil Flashcards
What are the alkenes
A homologous series of hydrocarbons with a general formula CnH2n
- unsaturated hyrocarbons contain c=c
Alkenes reacting with bromine
An addition reaction (bromide molecules adds to the double bond)
Ethene + bromine -> 1,2 dibromoethene
H. H
H. C. C. H
Br. BrHow to test for alkenes
Bromine water
This is orange/brown - turns colourless in the presence of alkanes as it reacts
Alkanes decolourise bromine water
Alkenes have no effect on the colour of bromine water I.e. It stays orange/brown
Why are short chain hydrocarbons more useful than long chain hydrocarbons
Burn better so make better fuels
What is cracking
Fractional distillation produces long chain hydrocarbons, which don’t burn well so there’s little Demand for them, but high demand for long chain
Cracking is a process in which long chain hydrocarbons are broken down into short chain hydrocarbons. An example of thermal decomposition.
Conditions for cracking
- crude oil is heated and vaporised
- vapours passed over a hot catalyst or mixed with steam and heated to a very high temp (600-700 degrees)
- thermal decomposition reaction occur
- the product is made up of both alkanes are alkenes
What is thermal decomposition
The breaking down of a substance using heat
Example of a cracking reaction
C10H22–> C5H12+C3H6=C2H4
what are plastics
large molecules made of small molecules joined together
the small molecules are called monomers and these polymerize to make large molecules called polymers
how do monomers join together
when alkene monomers join together the double bond opens up and connects with a neighboring monomer. single bonds form between carbon atoms, this reaction is called ADDITION POLYMERISATION
Define isomer
A compound with the same molecular formulae but different displayed formulae
