Alkanes

Oil is pre-heated * then passed into column. * The fractions condense at different heights * The temperature of column decreases upwards * The separation depends on boiling point. * Boiling point depends on size of molecules. * The larger the molecule the larger the van der waals forces * Similar molecules (size, bp, mass) condense together * Small molecules condense at the top at lower temperatures * and big molecules condense at the bottom at higher temperatures.

conversion of large hydrocarbons to smaller hydrocarbon molecules by breakage of C-C bonds

The petroleum fractions with shorter C chains (e.g. petrol are in more demand than larger fractions.

High pressure (7000 kPa) High temperature (400°C to 900°C)

produces mostly alkenes e.g. ethene used for making polymers and ethanol e.g C8H18 -> C6H14 + C2H4

Conditions: Slight or moderate pressure High temperature (450°C) Zeolite

Produces branched and cyclic alkanes and aromatic hydrocarbons cheaper than thermal cracking because less energy is used

they readily burn completely in the presence of oxygen they are highly exothermic

flue gas desulfurisation removes SO2 from the waste gases in furnaces . The gases pass through a scrubber containing basic calcium oxide which reacts with the acidic sulfur dioxide in a neutralisation reaction. SO2 + CaO –> CaSO3

Nitrogen oxides form from the reaction between N2 and O2 inside the car engine. The high temperature and spark in the engine provides sufficient energy to break strong N2 bond

These remove CO, NOx and unburned hydrocarbons (e.g. octane, C8H18) from the exhaust gases, turning them into ‘harmless’ CO2 , N2 and H2O.

2 CO + 2 NO –>2 CO2 + N2 C8H18 + 25 NO –>8 CO2 + 12½ N2 + 9 H2

Converters have a ceramic honeycomb coated with a thin layer of catalyst metals platinum, palladium, rhodium – to give a large surface area. .

UV wavelength radiation passes through the atmosphere to the Earth’s surface and heats up Earth’s surface. The Earth radiates out infrared long wavelength

In the presence of UV light alkanes react with chlorine to form a mixture of products with the halogens substituting hydrogen atoms

Step one: initiation Step two: propagation Step three: termination

Cl2 –> 2Cl .

A free radical is a reactive species which possess an unpaired electron.

when a free radical reacts with CH4 + Cl.  HCl + .CH3 Step two: Propagation .CH3 + Cl2  CH3Cl + Cl