organic chem

• Crude oil is a finite resource found in rocks. Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud.
• Most of the compounds in crude oil are hydrocarbons, which are molecules made up of hydrogen and carbon atoms only.

  Most of the hydrocarbons in crude oil are hydrocarbons called alkanes. 
• The first four members of the alkanes are methane, ethane, propane and butane
• The many hydrocarbons in crude oil may be separated into fractions, each of which contains molecules with a similar number of carbon atoms, by fractional distillation
• boiling point, viscosity and flammability change with increasing molecular size.
• The combustion of hydrocarbon fuels releases energy. During combustion, the carbon and hydrogen in the fuels are oxidised. The complete combustion of a hydrocarbon produces carbon dioxide and water
• Cracking can be done by various methods including catalytic cracking and steam cracking
• The products of cracking include alkanes and another type of hydrocarbon called alkenes.
• Alkenes are more reactive than alkanes and react with bromine water, which is used as a test for alkenes.
• There is a high demand for fuels with small molecules and so some of the products of cracking are useful as fuels.
• Alkenes are hydrocarbons with a double carbon-carbon bond. 
• The general formula for the homologous series of alkenes is Cn H2n

  Alkene molecules are unsaturated because they contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms
• The first four members of the homologous series of alkenes are ethene, propene, butene and pentene.
• Alkenes are hydrocarbons with the functional group C=C.

  It is the generality of reactions of functional groups that determine the reactions of organic compounds.
• Alkenes react with oxygen in combustion reactions in the same way as other hydrocarbons, but they tend to burn in air with smoky flames because of incomplete combustion.