1) PTHH: \(Mg+2HCl\rightarrow MgCl_2+H_2\uparrow\)
2) Ta có: \(n_{Mg}=\dfrac{1,2}{24}=0,05\left(mol\right)=n_{H_2}\) \(\Rightarrow V_{H_2}=0,05\cdot22,4=1,12\left(l\right)\)
3)
+) Cách 1: Tính theo phương trình
Theo PTHH: \(n_{HCl}=2n_{Mg}=0,1mol\) \(\Rightarrow m_{HCl}=0,1\cdot36,5=3,65\left(g\right)\)
+) Cách 2: Bảo toàn khối lượng
Ta có: \(\left\{{}\begin{matrix}m_{H_2}=0,05\cdot2=0,1\left(g\right)\\m_{MgCl_2}=0,05\cdot95=4,75\left(g\right)\end{matrix}\right.\)
\(\Rightarrow m_{HCl}=m_{MgCl_2}+m_{H_2}-m_{Mg}=4,75+0,1-1,2=3,65\left(g\right)\)
+) Cách 3: Bảo toàn nguyên tố (Bonus)
Theo PTHH: \(n_{MgCl_2}=n_{H_2}=0,05mol\) \(\Rightarrow\left\{{}\begin{matrix}n_{Cl}=0,1mol\\n_H=0,1mol\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}m_{Cl}=0,1\cdot35,5=3,55\left(g\right)\\m_H=0,1\cdot1=0,1\left(g\right)\end{matrix}\right.\) \(\Rightarrow m_{HCl}=3,55+0,1=3,65\left(g\right)\)
