-calculez masa de brom dizolvat in solutiec/100= md/ms--> 4/100= md/320---> md=12.8g brom-2cuatiile reactiilorCH2=CH2 +Br2---> CH2Br-CH2Br ori a moliCH≡CH +2Br2---> CHBr2-CHBr2 ori b moli-fac bilantul masei de brom ce intra in reactii si egalez cu masa obtinuta/(a+2b)molx160g/mol= 12,8dar a/b=2/3-rezolva sistemul, afla a si b-calculeaza masele de etena si etinam= a,molx 28g/mol=m= b,molx26g/mol= CALCULEAZA !