Akares RA(TIONAL DIStiLLATION
12.( ALIKANEs , 12. 2
Saturated hydrocarbon a compound contain1ng only hydrogen and carbon atoms,
with only (c
(-( and (-H sngle bonds.
General tormula of a chan alkane -CnH2nt
Alkanes are almost non-polart the electro negatvities af carbon and hydrogen are
Similar. The only internolecular force is Van der Waals, and the larger the
molecule, the stronger the Van der Waals. There fore boil1n point increases as
ham length increases
Alkanes with branched chans have lower melting_ponts than stroight chan allkanes.
wth the same nusnber ot carbon atoms. they contt pack as closely as unbranched
chans so Van der Waals forces are not as effectve
Alkanes are nsoluble in water but mik w1th other non-poar liquds.
Alkanes are relatively unreactive. they do bum and will react with halagens
under sustable cond1tons
Fractional dist1llation
Alkanes ore found in crude ol, formed by breakdown of animal and plant remans at
high tempesature and presS ure. There are other compounds d1ssalved in it, for ex ample,
contain1ng sulphur.
bottoe
- lrude oil is heated in a furnace and passes into a tower thats ooler at top than
vapours pass up until they reach a sutficiently cool tray and condense
Shorter chan alkanes candense nearer the top as they have lower boilng ponts
Thick residue at base is btumen (tar) and can be uscd for road surfacing
12.( ALIKANEs , 12. 2
Saturated hydrocarbon a compound contain1ng only hydrogen and carbon atoms,
with only (c
(-( and (-H sngle bonds.
General tormula of a chan alkane -CnH2nt
Alkanes are almost non-polart the electro negatvities af carbon and hydrogen are
Similar. The only internolecular force is Van der Waals, and the larger the
molecule, the stronger the Van der Waals. There fore boil1n point increases as
ham length increases
Alkanes with branched chans have lower melting_ponts than stroight chan allkanes.
wth the same nusnber ot carbon atoms. they contt pack as closely as unbranched
chans so Van der Waals forces are not as effectve
Alkanes are nsoluble in water but mik w1th other non-poar liquds.
Alkanes are relatively unreactive. they do bum and will react with halagens
under sustable cond1tons
Fractional dist1llation
Alkanes ore found in crude ol, formed by breakdown of animal and plant remans at
high tempesature and presS ure. There are other compounds d1ssalved in it, for ex ample,
contain1ng sulphur.
bottoe
- lrude oil is heated in a furnace and passes into a tower thats ooler at top than
vapours pass up until they reach a sutficiently cool tray and condense
Shorter chan alkanes candense nearer the top as they have lower boilng ponts
Thick residue at base is btumen (tar) and can be uscd for road surfacing
