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Discussion in 'Science' started by scienceteacher11, Apr 15, 2011.
Have you searched the resources section KS4 - carbon chemistry - hydrocarbons there are a number of resources. My class enjoyed https://www.tes.co.uk/teaching-resource/Alkanes-and-Alkenes-HC-Space-worksheet-3010365/
how about some combustion demos,
whoosh bottlle with suitable alcohol
saturated unsaturated test using bromine water, try different oils/spreads/butter/marg
make a song!!
separating crude oil and testing the fractions.demo
cracking paraffin. class prac.
woosh bottle as said before is fantastic. demo.
building the alkanes/alkenes.
CLEAPSS have a couple of different recipes for crude oil substitute, to get the gloopy nasty stuff add black oil paint to make it as thick as you want, alternatively carbon powder can be added to the 'crude oil'.
The substitute stuff is unconvincing, as is the practical.
I tend to do the ideas of fractional distillation quite fast, then compare fractions using hexane for petrol, 100-120 pet ether as naphtha, white spirit as diesel, 3 in 1 as lubricating oil, liquid paraffin as fuel oil.
Demo the flammability then do drip races down microscope slides to compare viscosity.
The old experiment was a goody though....
I remember finding this factional distillation of crude oil in a Nuffield Book of Collected Experiments. In that version, it was carried out in a side arm boiling tube and that what should always be used for this demonstration. The CLEAPSS mixture was produced because benzene is a Class 1 carcinogen (ie, identified in metabolic pathways leading to producing cancers) and hence banned from use in all industry (unless there is no other alternative) since 1988 as a result of the COSHH Regulations. The CLEAPSS mixture contains the chemicals quoted by Phlogiston along with Ivory Black oil paint available from an art shop to give the black colour. The recipe is on the Hazcards or the Recipe cards. I remember seeing a sample of crude and the mixture has the same consistency of a light crude oil (like Brent crude I think) as opposed to a heavy highly viscous crude oil like Venezuelan crudeI can collect several fractions (certainly more than 3) up to temperatures of 300C from 6 to 8 cm3 of the mixture, collecting the distillates in small test tubes. You can see changes in viscosity and ease of burning. I suggest you only collect a small amount of the first fraction (up to 80C) to show a non-smoky flame. As an extension, comparison of the heights of the distillates in the test tubes with 1cm3 of water in a similar test tube gives some idea of volume of each of the fractions. A pie chart can be produced of volume including that which does not distil; it is this fraction which is ‘cracked’ to produce more useful products including alkenes, the starting point of the plastics industry. What you should not use to distil crude oil is a fractionating column attached to a flask. It cannot get hot enough to give several fractions. If a fractionating column needs to be demonstrated I distilled an aqueous solution of ethanol (about 20%) which did not catch fire, but the first drops of the distillate did catch fire. In a previous job I had to carry out high-temperature fractionating and we used a heated fractionating column. The column was wrapped in asbestos tape containing heating wire which heated the asbestos and keeping the column hot!
making flubber with borax and pva
Modelling the molecules with MOLYMOD kits can be quite engaging for students. It not only forces them to recall the structure but also the bonds involved and the shape of the molecule.
This also leads on nicely to polymerisation as the whole class can make the same molecule in small groups them combine these models in to a single model of a polymer.
The methane bubble pratical is probably one of the most popular praticals that I have seen in relation to this topic though. It is always a crowd pleaser. I suppose it could also work quite nicely when talking about uses for the hydrocarbons .
You can do some modelling activities e.g. for cracking have 8 students hold hands in a chain which represents 8 carbons held together by single bonds (butane). Have 2 students leave the chain and hold both of each others arms. This represents ethene with a double bond and you are left with 6 students which are hexane. You can also model polymerisation by having pairs joining together to form a large chain. Its a good opportunity to investigate 'How models work' as you can ask questions such as 'What is good & bad about the model?' or get students to make their own model.
We have quite a few Hydrocarbon lesson planning resources on TES Resources which might give you a bit of inspiration. Check them out - Hydrocarbon resources
Hi I make paper mache models of the alkanes / alkenes