Why is crude oil important as a source of new materials?Alkanes
Crude oil is a finite resource. It can be separated into its useful fractions by fractional distillation. Some fractions undergo cracking to help meet demand for the smaller molecules.
Crude oil is mostly made up of a group of hydrocarbonA compound that contains hydrogen and carbon only. called the alkaneSaturated hydrocarbon. A compound of hydrogen and carbon only, with no C=C bonds..
A homologous seriesA 'family' of organic compounds that have the same functional group and similar chemical properties. is a series of molecules which:
have the same general formulaAn algebraic formula that sets out a rule or trend which is followed by all members of a homologous series. For example, all non-cyclic alkanes have the general formula CnH2n+2.
differ by CH2 in the molecular formulaChemical formula showing the actual number of atoms of each element in a molecule. of neighbouring compounds
show a gradual variation in physical propertiesA description of the appearance of a substance or how it acts without involving chemical reactions. For example, state, melting point, conductivity, etc.
have similar chemical properties
The table shows four alkanes, their molecular formula, displayed formula and ball-and-stick model diagram.
General formula
The formula of any alkane can be worked out using the general formula CnH2n+2 where n = the number of carbon atoms.
For example, for a hydrocarbon with ten carbon atoms:
n = 10 and 2n+2 = 22
the formula is C10H22
Question
Work out the formula for a hydrocarbon molecule with 6 carbon atoms.