PTHH: \(Mg+2HCl\rightarrow MgCl_2+H_2\uparrow\)

            \(2Al+6HCl\rightarrow2AlCl_3+3H_2\uparrow\)

            \(Fe+2HCl\rightarrow FeCl_2+H_2\uparrow\)

a) Ta có: \(\left\{{}\begin{matrix}n_{HCl}=\dfrac{12,7}{36,5}=\dfrac{127}{365}\left(mol\right)\\n_{H_2}=\dfrac{3,36}{22,4}=0,15\left(mol\right)\end{matrix}\right.\)

Ta thấy: \(2n_{H_2}< n_{HCl}\) \(\Rightarrow\) Axit còn dư

b) Theo PTHH: \(n_{HCl\left(p/ứ\right)}=2n_{H_2}=0,3\left(mol\right)\) \(\Rightarrow m_{HCl}=0,3\cdot36,5=10,95\left(g\right)\)

Mặt khác: \(m_{H_2}=0,15\cdot2=0,3\left(g\right)\)

Bảo toàn khối lượng: \(m_{muối}=m_{KL}+m_{HCl\left(p/ứ\right)}-m_{H_2}=18,65\left(g\right)\)

\(n_{H_2}=\dfrac{3,36}{22,4}=0,15\left(mol\right)\\ 2K+2H_2O\rightarrow2KOH+H_2\\ 2Na+2H_2O\rightarrow2NaOH+H_2\\ KOH+HCl\rightarrow KCl+H_2O\\ NaOH+HCl\rightarrow NaCl+H_2O\\ n_{HCl}=n_{KOH}+n_{NaOH}=2.n_{H_2}=2.0,15=0,3\left(mol\right)\\ m_{HCl}=0,3.36,5=10,95\left(g\right)\)

\(n_{H_2}=\dfrac{11,2}{22,4}=0,5\left(mol\right);n_{ZnCl_2}=\dfrac{27,2}{136}=0,2\left(mol\right)\)

PTHH(1): 2Al + 6HCl → 2AlCl₃ + 3H₂

Mol:     0,2                                  0,3

PTHH(2): Zn + 2HCl → ZnCl₂ + H₂

Mol:     0,2                      0,2      0,2

Ta có: \(n_{H_2\left(1\right)}=0,5-0,2=0,3\left(mol\right)\)

\(m_{hh}=0,2.27+0,2.65=18,4\left(g\right)\)

thiếu đề ạ ?

\(n_{H_2}=\dfrac{3.36}{22.4}=0.15\left(mol\right)\)

\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)

\(0.1..................................0.15\)

\(m_{Al}=0.1\cdot27=2.7\left(g\right)\)

\(m_{Cu}=10-2.7=7.3\left(g\right)\)

\(\%m_{Al}=\dfrac{2.7}{10}\cdot100\%=27\%\)

\(\%m_{Cu}=73\%\)

nHCl (ban đầu) = 0,35 . 2 = 0,7 (mol)

nH2 = 6,72/22,4 = 0,3 (mol)

PTHH: 

Mg + 2HCl -> MgCl2 + H2 (1)

2Al + 6HCl -> 2AlCl3 + 3H2 (2)

Fe + 2HCl -> FeCl2 + H2 (3)

Theo PTHH (1)(2)(3): nHCl (p/ư) = 2nH2 = 2 . 0,3 = 0,6 (mol)

So sánh: 0,6 < 0,7 => HCl dư

mHCl (p/ư) = 0,6 . 36,5 = 21,9 (g)

mH2 = 0,3 . 2 = 0,6 (g)

Áp dụng ĐLBTKL, ta có:

mkl + mHCl = m(muối) + mH2

=> m(muối) = 16 + 21,9 - 0,6 = 37,3 (g)