Chemistry C2 -Edexcel

Chemistry C2

Crude oil

Crude oil fractions burn cleanly so they make good fuels.

Crude oil provides raw materials for plastics and chemicals e.g. paints, detergents and medicines.

Crude oil = mainly carbon. Each carbon atom has 4 covalent bonds. Can have single, double or triple covalent bonds.

It is not infinite, it will run out but there are alternatives for things such a fuels.

Alkanes and Alkenes

 Alkanes have all C – C single bonds, saturated (no spare bonds). Methane, Ethane, Propane, Butane.

Alkenes have a C = C double bond. Unsaturated (decolourise bromine water). Form polymers by opening up their double bonds to form a chain. Ethene, Propene, Butene.

Alkenes react with water to make alcohols – hydration.

Cracking Hydrocarbons

Cracking – splitting up a long chain of hydrocarbons to form smaller, more useful, ones.

Cracking paraffin.

1)      Heat the paraffin.  After a few seconds move the Bunsen to heat the porcelain chips (catalyst). Alternate between the two until the paraffin vaporises and the porcelain glows red.

2)      The heated paraffin vapour cracks as it passes over the heated porcelain.

3)      Small alkanes collect at the end of the boiling tube, whilst alkene gases travel down the delivery tube.

4)      The alkenes are collected through water using a glass jar.

Vegetable oils

Unsaturated oils are better for your health than saturated ones because of what they do to the amount of cholesterol in your blood.

Unsaturated oils are runnier than saturated ones.

Vegetable oils are hydrogenated for the food industry – turns an unsaturated oil into a saturated one (breaks a hydrogen bond and adds a hydrogen) A nickel catalyst is needed to help.

Plastics

Plastics are long chain molecules called polymers.

Addition polymers are made under high pressure and using a catalyst. Addition polymers are made up of monomers that open their double bonds to join with the other carbon atoms (with no double bonds).

Plastics don’t rot so they’re hard to get rid of. Toxic gasses are given off if you burn plastic. It is best to recycle them to conserve resources.

Forces between molecules determine the properties of the plastics.

Weak forces: long chains with weak forces so free to move over each other. You can melt down and remould these plastics = thermoplastic polymers.

Strong forces: stronger bonds called crosslinks that hold the chains firmly together. Doesn’t soften when heated but too much heat makes it burn.

Drug synthesis

Drug testing can take over 10 years and cost millions:

1)      Tests on living cells or animals.

2)      Phase one: drug is tested on human volunteers – usually healthy people and doses are given steadily building up to the required level.

3)      Phase two: small numbers of people actually suffering from the disease are treated.

4)      Phase three: larger groups are tested, some are given drug and some are given placebo. Carefully monitored to see side effects  and if the drug actually works.

Drugs are developed using…