MA = 44,5 . 2 = 89 (g/mol); nCO2=13,2/44=0,3 mol; nH2O=6,3/18=0,35 mol; nN2=1,12/22,4=0,05 mol
nC=nCO2=13,2/44=0,3 mol
nH=2nH2O=0,7 mol
nN=2nN2=0,1 mol
mO=meste-mC-mH-mN = 8,9-0,3.12-0,7.1-0,1.14=3,2 gam => nO=3,2/16=0,2 mol
=> C:H:O:N = 0,3:0,7:0,2:0,1 = 3:7:2:1
=> CTĐGN: C3H7O2N
Mà MA = 89 => CTPT: C3H7O2N
CTCT: H2N-CH2-COOCH3 (A); H2N-CH2-COOH (B)