\(\dfrac{56x}{16y}= \dfrac{72,144\%}{27,856\%}\\ \Rightarrow\dfrac{x}{y} = \dfrac{72,144\%}{27,856\%} : \dfrac{56}{16} = 0,75 = \dfrac{3}{4}\)
Gọi công thức E là FexOy
=>M(FexOy)=56x+16y(g/mol)
có %Oxi=16y=15,6x+4,46y<=>11,54y=16x=>11,54y=15,6x=>xy=11,5415,6≈3/4