HO-CH2-CH(NH2)-COOH
F.m. = C3H7NO3, M = 3x12+7x1+14+16x3 = 105 g/mol
105g serina..... 3x12g C ....... 7x1g H ...... 14g N ...... 3x16g O
100% ................. x% ................ y% ................ z% ........... t%
x = 34,28% C
y = 6,67% H
z = 13,33% N
t = 45,72% O