Nitrogen compounds Flashcards
How does having a double bond change the chemistry of a hydrocarbon?
The double bond makes alkenes more reactive than alkanes
. One type of reaction involving alkenes is called an addition reaction. This is where a small molecule is added to a C=C double bond, leaving a single bond in its place. The atoms of the small molecule attach to the carbon atoms in the alkene.
What is the addition reaction of Br2 used for
This is a good test for alkenes, as the orange bromine (or bromine water, which is safer to use than pure bromine) turns colourless as the reaction happens.
For example the addition of Br2 to ethene.
What is the addition reaction of H2 used for
This requires a nickel catalyst and is commonly known as hydrogenation. It is used in the production of margarine.
An example of an addition reaction of H2 is the reaction of H2 to ethene.
What happens during polymerisation
The alkene is known as a monomer (a small reactive molecule that, when joined together with others of its kind, forms a polymer).
During polymerisation, one of the bonds in the double bonds breaks and then joins onto another monomer. This process repeats until a long polymer chain is formed.
What polymer has formed from which monomer and what is it used for
1)
Ethene polymerises to form poly(ethene), which is used for plastic bags and bottles.
2)
Propene polymerises to form poly(propene), which is used for ropes and plastic crates.
3)
Vinyl chloride polymerises to form poly(vinyl chloride), also known as PVC, which is used for drainpipes and window frames.
4)
Tetrafluoroethene polymerises to form poly(tetrafluoroethene), also known as PTFE or Teflon, which is used for non-stick coatings for pans.
Why is disposing plastic problematic
Disposing of plastic in landfills is not effective as landfills quickly fill up and plastic waste will not decompose for hundreds of years as it is not biodegradable and is highly resistant to most chemical reactions.
Burning plastics is not desirable as they release carbon dioxide as they burn (contributing to global warming). They also release a number of toxic gases as they burn.
Why is recycling positive for the environment
Recycling plastic is the most effective solution to this problem as it reduces the amount of plastic waste that is going to landfills or being burned.
Recycling helps conserve crude oil reserves, as less new plastic is required.
Finally, recycling uses less energy than producing new plastics and so fewer fossil fuels need to be burned.
