Bài 1:
a) \(\%Fe=\frac{56\cdot3}{232}\cdot100\approx72,4\%\) \(\Rightarrow\%O\approx27,6\%\)
b) \(\%K=\frac{39}{101}\cdot100\approx38,6\%\)
\(\%N=\frac{14}{101}\cdot100\approx13,9\%\)
\(\Rightarrow\%O\approx47,5\%\)
Bài 3:
PTHH: \(Zn+2HCl\rightarrow ZnCl_2+H_2\)
a) Ta có: \(n_{Zn}=\frac{13}{65}=0,2\left(mol\right)\) \(\Rightarrow n_{H_2}=0,2mol\)
\(\Rightarrow V_{H_2}=0,2\cdot22,4=4,48\left(l\right)\)
b) Theo PTHH: \(\left\{{}\begin{matrix}n_{Zn}=n_{ZnCl_2}=0,2mol\\n_{HCl}=0,4mol\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}m_{HCl}=0,4\cdot36,5=14,6\left(g\right)\\m_{ZnCl_2}=0,2\cdot136=27,2\left(g\right)\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}C\%_{ddHCl}=\frac{14,6}{200}\cdot100=7,3\%\\C\%_{ZnCl_2}=\frac{27,2}{200+13}\cdot100\approx12,77\%\end{matrix}\right.\)
