Cho $\begin{cases} Fe:x(mol)\\ Zn: y(mol)\\\end{cases}$
`n_{H_2}=\frac{4,48}{22,4}=0,2(mol)`
`n_{SO_2}=\frac{5,6}{22,4}=0,25(mol)`
BTe:
$\mathop{Fe}\limits^{0}\to \mathop{Fe}\limits^{+2}+2e\ || \ \mathop{2H}\limits^{+}+2e\to \mathop{H_2}\limits^{0}$
$\mathop{Zn}\limits^{0}\to \mathop{Zn}\limits^{+2}+2e$
$\mathop{Fe}\limits^{0}\to \mathop{Fe}\limits^{+3}+3e \ || \ \mathop{S}\limits^{+6}+2e\to \mathop{S}\limits^{+4}$
`2n_{Fe}+2n_{Zn}=2n_{H_2}`
`=> 2x+2y=0,4(mol)(1)`
`3n_{Fe}+2n_{Zn}=2n_{SO_2}`
`=> 2x+2y=0,5(mol)(2)`
`(1),(2)=> x=y=0,1(mol)`
`a)` `%m_{Zn}=\frac{65.0,1.100%}{0,1(65+56)}\approx 53,72%`
`%m_{Fe}=100%=53,72%=46,28%`
`b)` Sửa đề: tính `m` gam dung dịch `H_2SO_4` `98%` đã dùng.
`n_{H_2SO_4}=2.n_{SO_2}=0,5(mol)`
`m_{\text{dd} H_2SO_4}=0,5.98.\frac{100}{98}=50g`