organic chemistry

• crude oil is a non-renewable resource
• crude oil is formed from the fossilised remains of ancient plankton
• crude oil is found in rocks and is used to produce fuels and other important chemicals
• crude oil is a mixture of lots of different compounds that are not chemically combined, most of them being hydrocarbons
• hydrocarbons are molecules made up of only hydrogen and carbon atoms, and differ in size which can change the properties of the hydrocarbon
• heavy fractions of crude oil do not make good fuels because they don't ignite easily, have high boiling points, and have low volatility
• most hydrocarbons found in crude oil are alkanes
• in alkanes, carbon atoms bond to four other atoms, called saturated hydrocarbons as they only contain single bonds with other atoms
• alkanes are quite unreactive but can burn well, making them useful fuels
• the general formula for alkanes is C^nH^(2n+2)
• a hydrocarbon's size affects its properties, affecting how useful it is as a fuel
• hydrocarbons with longer chains have higher boiling points
• hydrocarbons with longer chains have higher viscosity
• hydrocarbons with longer chains are less flammable
• the equations for the combustion of hydrocarbons depend on the amount of oxygen that is available
• the combustion of hydrocarbons when there is a good air supply involve energy release, and the oxidation of carbon and hydrogen to create carbon dioxide and water
• if alkanes are burned without enough oxygen, then carbon monoxide can be created, which is a colourless, odourless, toxic gas
• fractional distillation is the process of separating crude oil into groups of hydrocarbons with similar numbers of carbon atoms, called 'fractions'
• hydrocarbons with lots of carbon atoms are called 'long-chain hydrocarbons'
• hydrocarbons with few carbon atoms are called 'short-chain hydrocarbons'
• different-sized hydrocarbons have different boiling points
• fractional distillation separates hydrocarbons using their different boiling points
• during fractional distillation, firstly, crude oil is heated until it evaporates, and the vapour is put into a fractionating column at the bottom and rises upwards
• during fractional distillation, secondly, the temperature is highest at the bottom of the column, where long-chain hydrocarbons condense at the bottom and are collected as liquids. short chain-hydrocarbons have lower boiling points, and pass up the column and condense at lower temperatures nearer the top
• during fractional distillation, finally, the fractions are collected and are then processed to create end products
• an alkane is an example of a homologous series
• cracking is the process that breaks down long-chain hydrocarbons into shorter-chain more useful molecules
• cracking is an example of a thermal decomposition reaction
• in catalytic cracking, vapourised heavy hydrocarbons are passed over a hot catalyst, and the products include alkanes and alkenes
• in steam cracking, vapourised heavy hydrocarbons are mixed with steam in a high temperature environment, and the products include alkanes and alkenes
• alkenes, like alkanes, are hydrocarbons
• alkenes are used as stating materials for chemicals like ethanol, and being combined to make polymers