2HNO3+Ba(OH)2=Ba(NO3)2+H2O
n(Ba(OH)2)=17,1g/171g/mol=0,1mol
m(HNO3)=0,2mol*63g/mol=12,6g
17.1 xBa(OH)2 + 2HNO3 = Ba(NO3)2 + 2H2O
