CH2=CH2 +Br2-----> CH2Br-CH2Br
m,apa brom, initiala= m,apa + m,brom
m, apa brom final= m,apa + m ,dibromoetan=
m,apa+ m,brom+m,etena
m,f-m,i= m,etena = 7g
M,etena= 28g/mol
n,etena= 7g/28g/mol= 0,25mol= n,brom
200ml sol...........0,25mol
1000ml............c=1,25M
nu stiu de ce da 0,5 ???