\(n_{Fe}=\dfrac{8,4}{56}=0,15mol\)

\(m_{CuCl_2}=\dfrac{270\cdot10\%}{100\%}=27g\Rightarrow n_{CuCl_2}=0,2mol\)

\(Fe+CuCl_2\rightarrow FeCl_2+Cu\)

0,15    0,2          0,15       0,15

\(a=m_{Cu}=0,15\cdot64=9,6g\)

\(m_{FeCl_2}=0,15\cdot127=19,05g\)

\(m_{ddFeCl_2}=8,4+270-0,15\cdot64=268,8g\)

\(C\%=\dfrac{19,05}{268,8}\cdot100\%=7,09\%\)

Đáp án A

Ÿ Chất rắn B nguyên chất nên B là Cu

=> Fe và Zn phản ứng hết.

Ÿ G là ZnO

\(n_{Mg}=\dfrac{2,4}{24}=0,1\left(mol\right)\\ m_{HCl}=\dfrac{109,5\cdot10\%}{100\%}=10,95\left(g\right)\\ \Rightarrow n_{HCl}=\dfrac{10,95}{36,5}=0,3\left(mol\right)\\ a,PTHH:Mg+2HCl\rightarrow MgCl_2+H_2\\ \text{Vì }\dfrac{n_{Mg}}{1}< \dfrac{n_{HCl}}{2}\text{ nên sau p/ứ }HCl\text{ dư}\\ \Rightarrow n_{H_2}=0,1\left(mol\right)\\ \Rightarrow V_{H_2\left(đktc\right)}=0,1\cdot22,4=2,24\left(l\right)\)

\(b,n_{MgCl_2}=0,1\left(mol\right)\\ \Rightarrow m_{CT_{MgCl_2}}=0,1\cdot95=9,5\left(g\right)\\ m_{H_2}=0,1\cdot2=0,2\left(mol\right)\\ m_{dd_{MgCl_2}}=2,4+109,5-0,2=111,7\left(g\right)\\ \Rightarrow C\%_{MgCl_2}=\dfrac{9,5}{111,7}\cdot100\%\approx8,5\%\)

\(n_{HCl}=\dfrac{10\%.109,5}{36,5}=0,3\left(mol\right);n_{Mg}=\dfrac{2,4}{24}=0,1\left(mol\right)\\ a,PTHH:Mg+2HCl\rightarrow MgCl_2+H_2\\ Vì:\dfrac{0,3}{2}>\dfrac{0,1}{1}\Rightarrow HCldư\\ n_{H_2}=n_{MgCl_2}=n_{Mg}=0,1\left(mol\right)\\ n_{HCl\left(p.ứ\right)}=2.0,1=0,2\left(mol\right)\Rightarrow n_{HCl\left(dư\right)}=0,3-0,2=0,1\left(mol\right)\\ V_{H_2\left(đkc\right)}=24,79.0,1=2,479\left(l\right)\\ b,ddA:HCl\left(dư\right),MgCl_2\\ m_{ddA}=2,4+109,5-0,1.2=111,7\left(g\right)\\ C\%_{ddHCl\left(dư\right)}=\dfrac{0,1.36,5}{111,7}.100\%\approx3,268\%;C\%_{ddMgCl_2}=\dfrac{0,1.95}{111,7}.100\%\approx8,505\%\)

Đáp án B

Đáp án B