Cracking, Polymerisation, alkenes and alkenes Flashcards
Alkenes are unsaturated hydrocarbons.
State what is meant by unsaturated.
It contains a double bond
Propane and propene are bubbled through separate samples of bromine water.
Describe what you would see in these tests.
Bromine water is orange
When Propane is bubbled through, the bromine water remains the same
When propene is bubbled through, bromine water becomes colourless
In industry, long chain hydrocarbon molecules are cracked to form shorter chain
hydrocarbon molecules.
Explain why this process is important.
Shorter chain molecules are more useful and are in higher demand
Cracking produces alkenes, which are used to polymers
In the cracking experiment, When the experiment is complete there is a danger that water will rise up the
delivery tube into the hot test tube.
State what you would do to prevent this.
Remove delivery tube from water
before stopping heating
Define the term cracking?
Cracking allows large hydrocarbon chain molecules into smaller, more useful hydrocarbon molecules
What is cracking an example of?
A thermal decomposition reaction
What are the products of cracking?
Alkenes
Define the term polymerisation
Process in which many small monomers join to make a long chain molecule
What is a polymer?
A polymer is a long chain molecule that is made through polymerisation
What is a monomer?
A molecule that can be bonded to other identical molecules to make a polymer
What is released when you burn polymers?
They release toxic chemicals
How can you dispose of polymers?
Bury them in landfill
Recycle them
Burn them
What are the advantages/disadvantages of recycling polymers?
The polymers aren’t wasted and we can reuse them
If we don’t recycle, we use up crude oil much quicker
We have to sort the polymers
This will cost money
What are the advantages/disadvantages of burying polymers in landfill?
It wastes the polymers
Polymers are non biodegradable therefore will remain for 100 hundreds of years
What are the advantages/disadvantages of burning polymers?
By burning, we can generate electricity
They give off toxic gases when burned
What are the uses of poly(ethene)
Plastic bags
Plastic bottles
Cling film
Insulation for electrical wires
What are the uses of poly(propene)
Buckets and bowls
Plastic bags
Packaging
What are the uses of poly(chloroethene) PVC
Window frames
Gutters
Pipes
Insulation for electrical wires
What are the uses of poly(tetrafluoroethene) PTFE
Non stick coatings for saucepans
Bearings and skis
Containers for corrosive substances
Stain proofing carpets
What are the properties of poly(ethene)
Flexible
Cheap
Good insulator
What are the properties of poly(propene)
Flexible
Shatterproof
High softening point
What are the properties of poly(chloroethene) PVC
Tough
Cheap
Long lasting
Good insulator
What are the properties of poly(tetrafluoroethene)
Tough
Slippery
Resistant to corrosion
Good insulator
What is the general formula for the number of hydrogen atoms in an alkane hydrocarbon?
No. Of H atoms = no. of carbon atoms x 2 +2
What is the general formula for the number of hydrogen atoms in an alkene hydrocarbon?
No. Of H atoms = no. of carbon atoms x 2
Propene is used to make the polymer poly(propene).
Explain how poly(propene) molecules are formed from propene molecules and
relate the properties of poly(propene) to its uses.
many propene molecules join/react together form a long chain through a polymerisation reaction propene is the monomer
propene is unsaturated / has a double bond
poly(propene) has single bonds
propene is a gas and forms poly(propene) which is a solid
The double bond breaks up
Flexible, low density, long lasting - packaging, plastic bags
