verificam 1,55-0,62-0,103 = 0,827 g O determinat prin diferenta
1,55g substanta ..... 0,62g C ...... 0,103g H ..... 0,827g O
100% ....................... a% .................... b% ................. c%
= 40% C = 6,65% H = 53,35% O
pentru Fb:
C = 0,62/12 = 0,052
H = 0,103/1 = 0,103
O = 0,827/16 = 0,0517 :0,052
=> Fb = CH2O
Fm = (CH2O)n
n = miuFm/miuFb, miuFb = 12+2+16 = 30 g/mol
=> n = 60/30 = 2
=> Fm = C2H4O2