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Ta có: \(n_{Fe}=\dfrac{5,6}{56}=0,1\left(mol\right)\)
a. PTHH: Fe + H2SO4 ---> FeSO4 + H2
b. Theo PT: \(n_{H_2}=n_{Fe}=0,1\left(mol\right)\)
=> \(V_{H_2}=0,1.22,4=2,24\left(lít\right)\)
c. Theo PT: \(n_{H_2SO_4}=n_{Fe}=0,1\left(mol\right)\)
=> \(m_{H_2SO_4}=0,1.98=9,8\left(g\right)\)
=> \(C_{\%_{H_2SO_4}}=\dfrac{9,8}{100}.100\%=9,8\%\)
PTHH: \(2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\uparrow\)
2a______3a__________a_______3a (mol)
\(Mg+H_2SO_4\rightarrow MgSO_4+H_2\uparrow\)
b_______b________b______b (mol)
Ta lập HPT: \(\left\{{}\begin{matrix}27\cdot2a+24b=7,8\\3a+b=\dfrac{200\cdot19,6\%}{98}=0,4\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}a=0,1\\b=0,1\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}m_{Mg}=0,1\cdot24=2,4\left(g\right)\\m_{Al}=5,4\left(g\right)\\n_{Al_2\left(SO_4\right)_3}=0,1\left(mol\right)=n_{MgSO_4}\\n_{H_2}=0,4\left(mol\right)\Rightarrow m_{H_2}=0,4\cdot2=0,8\left(g\right)\end{matrix}\right.\)
Mặt khác: \(m_{dd}=m_{KL}+m_{ddH_2SO_4}-m_{H_2}=207\left(g\right)\)
\(\Rightarrow\left\{{}\begin{matrix}C\%_{Al_2\left(SO_4\right)_3}=\dfrac{0,1\cdot342}{207}\cdot100\%\approx16,52\%\\C\%_{MgSO_4}=\dfrac{0,1\cdot120}{207}\cdot100\%\approx5,8\%\end{matrix}\right.\)
200ml = 0,2l
\(n_{KOH}=1.0,2=0,2\left(mol\right)\)
Pt : \(2KOH+H_2SO_4\rightarrow K_2SO_4+2H_2O|\)
2 1 1 2
0,2 0,1
\(n_{H2SO4}=\dfrac{0,2.1}{2}=0,1\left(mol\right)\)
⇒ \(m_{H2SO4}=0,1.98=9,8\left(g\right)\)
\(C_{ddH2SO4}=\dfrac{9,8.100}{49}=20\)0/0
Chúc bạn học tốt
\(a.n_{H_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\\ Đặt:\left\{{}\begin{matrix}n_{Al}=a\left(mol\right)\\n_{Mg}=b\left(mol\right)\end{matrix}\right.\left(a,b>0\right)\\ 2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\\ Mg+H_2SO_4\rightarrow MgSO_4+H_2\\ \rightarrow\left\{{}\begin{matrix}27a+24b=5,1\\1,5a+b=0,25\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,1\\b=0,1\end{matrix}\right.\\ \left\{{}\begin{matrix}\%m_{Al}=\dfrac{27.0,1}{5,1}.100\approx52,941\%\\\%m_{Mg}\approx47,059\%\end{matrix}\right.\)
\(b.m_{ddH_2SO_4}=\dfrac{0,25.98.100}{9,8}=250\left(g\right)\\ m_{ddsau}=m_{Al,Mg}+m_{ddH_2SO_4}-m_{H_2}=5,1+250-0,25.2=254,6\left(g\right)\\ C\%_{ddAl_2\left(SO_4\right)_3}=\dfrac{0,05.342}{254,6}.100\approx6,716\%\\ C\%_{ddMgSO_4}=\dfrac{0,1.120}{254,6}.100\approx4,713\%\)
\(n_{Fe}=\dfrac{5,6}{56}=0,1\left(mol\right)\)
PTHH: Fe + H2SO4 → FeSO4 + H2
Mol: 0,1 0,1
\(C\%_{ddH_2SO_4}=\dfrac{0,1.98.100\%}{100}=9,8\%\)