Formula moleculara a alcanilor: CnH2n+2;    μ =12n+2n+2, g/mol
in 100    g alcan sunt  82,75g   C
in 14n+2  g alcan  ....    12n gC      100x12n=82,75(14n+2)  => n=4
CH3-CH-CH3 Â Â Â Â Â 2METIL PROPAN
     CH3
PRIN DEHIDROGENARE rezulta 2metil propena si H2
CH2=C(CH3)-CH3 Â +H2
PRIN CRACARE rezulta metan si propena
CH4 + CH2=CH-CH3