Trebuie sa afli masele de C ,H,O, care se gasesc in 100g alcool !!!
CH2OH-CHOH-CH2OH sau C3H8O3
M= 3x12gC+8x1gH+3x16gO----> 92g//mol
in 92g alcool.........36gC.......8gH.......48gO
100g.....................x.........y.............z
calculeaza x,y,z !!!!