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C1.5 polymers
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- 1define cracking? and why we do it?splitting up long-chain hydrocarbons. we do it because long-chain hydrocarbons form thick gloopy liquids which are not useful so a lot of longer molecules produced from fractional distillation are turned into smaller ones by cracking. useful for petrol and paraffin for jet fuel
- 2describe the process of crackingit is a thermal decomposition reaction. first, heat the long chain hydrocarbon to vaporise it (turn it to gas). the vapour is passed over a powdered catalyst (aluminium oxide) at a temp between 400 - 700. the long chain molecules 'crack' on the surface of the catalyst.
- 3what bond does an alkENE have?a C=C double bond between two of the carbon atoms in their chain. are known as unsaturated because they can make more bonds (can open up allowing to carbon atoms to bond with other atoms.
- 4what is the general formula of an alkENE?C(n)H(2n)
carbon atoms always make four bonds, hydrogen only makes one, double bonds still allow carbons to make 4 bonds
ethene: H H
C=C
H H - 5describe the test for an alkeneadd the substance to bromine water. an alkene will turn the bromine water from orange to colourless, because the double bonds have opened and formed bonds with the bromine.
- 6how can ethene be reacted with steam to produce ethanol? what are the advantages and disadvantages?it can be hydrated with steam in the presence of a catalyst to make ethanol.
adv: cheap because ethene is cheap and not much of it is wasted.
disadv: ethene is produced from crude oil which is a non renewable source that is running out. could start becoming expensive - 7how can ethanol be produced with renewable resources?fermentation. sugar is converted to ethanol using yeast.
sugar = carbon dioxide + ethanol
pro: lower temp, simpler equip. sugar is renewable and is a major growing crop. this ethanol can be used as a cheaper fuel in poor countries
con: not very concentrated. to increase strength must distill and purify. - 8define polymerisationjoining together lots of small alkene molecules (monomers) to form very large molecules (polymers)
- 9describe polymers physical properties and how this makes them suitable for different usestheir physical properties are affected by the temp and pressure of polymerisation.
light stretchable ones are used for plastic bags. elastic polymer fibres are used to make lycra for tights. biodegradable packaging are made from polymers and cornstarch. - 10why are polymers hard to get rid of? why are they getting more expensive?most aren't biodegradable. they are difficult to get rid of. if buried in a landfill site, they'll still be there years later. best thing is to reuse them and recycle them. things made form polymers are cheaper than made form metal. however as crude oil resources get used up, the price of crude oil will rise.
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- GCSE Science Flashcards on C1.5 polymers , created by leonie jones on 09/11/2015.
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