y 640 g x
Fe+CuSO4=FeSO4+Cu
56 160 64
dintr-o sol. react. numai md
md=c.ms:100
md=800.80:100=640gCuSO4
X=640.64:160=256gCu
y=640.56:160=224gFe pur
se calculeaza cant. de Fe care are si impuritati
100g------------70g Fe pur
a ----------------224g Fe pur
a=100.224:70=320g Fe cu impuritati