Răspuns :
54,54 /12 = 4,54
9.09 / 1 = 1
36,36 / 16 = 2, 27
impartim pe fiecare cu 2,27 => C = 2
H = 4
O = 1 => formula bruta C2H4O - acetaldehida sau etanal => formula moleculara CH3CHO
transform raportul de mase in raport molar, stiind M,C=12g/mol,M,H=1g/mol M,O=16g/mol si niu=m/M
nC:nH:nO= 54,54/12 : 9,09/1 : 36,36/16
=4,545: 9,09:2,27 imprtind prin cel mai mic numar
=2 :4:1
f.b= C2H4O
F.M. (C2H4O)n-------> 88= n(24gC+4gH+16gO)---> n=2 C4H8O2