1)
Fe => FeCl2 => Fe(OH)2 => Fe(OH)3 => Fe(NO3)3 => Fe2O3
Fe+ 2HCl= FeCl2+ H2
FeCl2+ 2KOH= Fe(OH)2+ 2KCl
2Fe(OH)2+ H2O+ 1/2O2= 2Fe(OH)3
Fe(OH)3+ 3HNO3= Fe(NO3)3+ 3H2O
2Fe(NO3)3 (t*)= Fe2O3+ 6NO2 + 3/2O2
2)
a, nH2SO4= 0,05 mol
R2Ox+ xH2SO4= R2(SO4)x+ xH2O
=> nR2Ox= 0,05/x mol
=> M R2Ox= 8x/0,05= 160x
=> M R= (160x-16x)/2= 72x
x=???
b,
2A+ Cl2 (t*)= 2ACl
nA= n muối
<=> 9,2/A= 23,4/(A+35,5)
<=> 9,2(A+35,5)= 23,4A
<=> A=23. Vậy A là Na