Organic Chemistry

General Formulas
Alkanes - CnH2n+2
Alkenes - CnH2n
Alcohols - CnH2n+1OH
Carboxylic Acid - CnH2n+1COOH

Isomers - Compounds that have the same molecular formula but different structural formulae

Alkanes - Saturated Hydrocarbons because they contain only single bonds
Alkenes - Unsaturated Hydrocarbons because they contain double bonds
(Any molecule which contains double bonds between carbon atoms is described as unsaturated)

Viscosity
The alkanes become more viscous, i.e more difficult to pour out. This is because long carbon chain s are much more likely to get tangled up. This makes it difficult for the liquid to flow.

Flammabilty
As the molecular sice of the alkane molecule increases, the percentage of carbon in the alkane molecule also increases. As a result, the alkane becomes less flammable, i.e more difficult to burn and the flame becomes smoky. The smoky flame is caused by incomplete combustion of carbon atoms

Combustion

Combustion of alkanes in excess air or oxygen produces carbon dioxide and water vapour.

Ch4(g) + 2O2(g) -heat-> CO2(g) + 2H2O(g)

2C2H6(g) + 7O2(g) -heat-> 4CO2(g) + 6H2O(g)

These reactions are highly exothermic, thus alkanes make good fuels

If there is an insufficient supply of air or oxygen, combustion of alkanes is incomplete and the product formed are carbon monoxide and water vapour.

2Ch4(g) + 3O2(g) -heat-> 2CO(g) + 4H2O(g)

or CH4(g) + O2(g) -heat-> C(g) + 2H2O(g)

Substitution reactions

Alkanes do not react with most chemicals but they do react with chlorine in the presence of UV light as a catalyst.

Methane + Chlorine -UV light-> Chloromethane + Hydrogen Chloride
CH4(g) + Cl2(g) -UV light-> CH3Cl(g) + HCl(g)

Manufacture of Alkenes

Alkenes are maufacture by the catalytic cracking of petroloeum. The breaking down of a long-chain hydrocarbon into smalled molecules is called cracking

Catalyst: Aluminium Oxide/Silicon Oxide
Condition: Hight Temperature - 600 degree celcius
Product: Short-Chain Alkane/Alkane

Cracking is used to produce high-grade petrol.

Additional reactions are reactions in which an unsaturated organic compund combines with another element or compound to form a new single compound.
(During reaction, the double bond is replaced by two single bonds.)

Hydrogenation

Catalyst:
Condition:
Procedure:
Equation:
Importance:

Bromination

Objective:
Catalyst:
Condition:
Product:
Equation:

Hydrogenation (Reaction with steam)

Catalyst:
Condition:
Product:
Equation:

Polymerisation (long-chained molecules)
Condition:

Polyunsaturated Fats and Oils:

Difference between fats and oils: