Tinand cont ca masa initiala reprezenta 100%, dupa aditia HCl, masa de cloroalchena reprezinta 153,67%
CnH2n-2 + HCl -> CnH2n-1Cl
Mcloroalchena=12n+2n-1+35,5=14n+34,5
14n+34,5...............153,67%
36,5..........................53,67%
14n+34,5=36,5*153,67/53,67=104,5
14n=70 => n=5
avem 1-pentina, 2-pentina si 3-metil-1-butina