din 1 mol CnH2n-2 rezulta 1mol CnH2n-3Ag ( reactie de substitutie)
14n-2,g........................................14n-3+108,g
10,8.g...............................................32,2g
32,2(14n-2)= 10,8(14n+105)
...................................calculeaza n inlocuieste in CnH2n-2 si afla alchina !!!