Răspuns:
MFe 56 g/mol;
MFeCl3 =1×56 + 3×35,5 = 162,5(g/mol).
100% - 12% = 88%.
100gFe.................88gFe pur
190,90gFe...........xg Fe pur
x = 190,90×88/100 = 167,992g Fe pur
2×56g ............. 2×162,5g
2Fe + 3Cl2 = 2FeCl3
167,992g...................yg
y = 167,992×2×162,5/2*56= calculează