2. alkanes

non renewable resource formed when animal remains are buried under high temperature and pressure in the absence of O2 over millions of years it is a valuable resource used in the process of making fuels, plastics, medicines alkanes are the main constituent of crude oil

saturated - each C forms max bonds. there are only C-C hydrocarbons - consist only of H and C

• Oil is heated to evaporation/vaporise it in blast furnace. it enters fractionating column • has a temp gradient where it is hottest at the bottom. Negative temperature gradient • short chain molecules have lower BP bc weaker imf and condense nearer the top. Vv: higher bp/ larger molecules at bottom • separate into fractions [fractions are mixtures of hydrocarbons with sim chain lengths and uses] of similar boiling points and chain lengths. Fractions are separated by bp Should yuo say Mr molecular size or chain length? 🤔

a physical process based on different bps and molecule sizes. it splits the weak vdw forced between molecules

breakdown/ conversion of long chain HCs into SC HCs by breaking C-C bonds this is done bc shorter chain alkanes are more in demand and more useful there is catalytic and thermal cracking

zeolite catalyst high temp of ~450C moderate pressure produces branched alkanes, cyclic alkanes, aromatic hydrocarbons

high temperature 800 high pressure 7000kPa or 70atm. 1atm = 100kPa produces alkenes

smth that releases heat energy when burned/ combusted they burn readily in oxygen, highly exothermic

releases less energy/mole and forms pollutants NOx gases SO2 C CO unburnt HCs

polar bonds absorbs ir radiation

they are in cars to remove CO and NOx and unburnt HCs to give CO2, N2 and H2O. 2CO+ 2NO - 2CO2 + N2 unburnt HC chains react with NO to form CO2, N2 and water it will have a platinum, palladium or rhodium catalyst

SO2 can be removed from flue gases using calcium oxide or calcium carbonate CaCO3 + SO2 -> CaSO3 + CO2

little polarity UV light has more energy providing Ea for bonds to break. in presence of UV X-X bond in halogen molecules break to form halogen free radicals f radicals are atoms/molecules with an unpaired electron

alkane + free radical -> alkane radical + hydrogen halide alkane radical + halogen molecule -> h.alkane + halogen radical

INITIATION UV forms f radicals from halogen molecules PROPAGATION molecule + radical -> molecule + radical TERMINATION - desired product - halogen molecule - side reaction where two alkane radicals form. in Qs always do structural formula

the synthesis of chlorofluorocarbons to be used as coolants or refrigerants was bad because they are unreactive so rise to stratosphere where UV is stronger. the CCl bond breaks and forms Cl• which reacts with O3 as a catalyst. one Cl• cand destroy thousands O3s.