notam compusul CnH2n+2-aBra, a = nr de atomi de Br din molecula compusului
100% ........................................... 75,074% Br
216 g ......................................... .. 80a g Br
=> a = 2 => compusul va avea forma CnH2nBr2
=> 14n+160 = 216 => n = 4
=> C4H8Br2
CH3 CH3 CH3 CH3
I I I I
H-C-Br Br-C-H Br-C-H H-C-Br
I I I I
Br-C-H H-C-Br Br-C-Br H-C-Br
I I I I
CH3 CH3 CH3 CH3
(1) (2) (3) (4)
