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\(a,m_{rắn}=m_{Cu}=2,7\left(g\right)\\ \Rightarrow m_{\left(Zn,Fe\right)}=12-2,7=9,3\left(g\right)\\ n_{H_2}=0,15\left(mol\right),n_{axit}=2.0,2=0,4\left(mol\right)\\ Đặt:n_{Zn}=a\left(mol\right);n_{Fe}=b\left(mol\right)\left(a,b>0\right)\\ PTHH:Zn+H_2SO_4\rightarrow ZnSO_4+H_2\\ Fe+H_2SO_4\rightarrow FeSO_4+H_2\\ Vì:\dfrac{0,15}{1}< \dfrac{0,4}{1}\Rightarrow axit.dư\\ \Rightarrow\left\{{}\begin{matrix}65+56b=9,3\\a+b=\dfrac{3,36}{22,4}=0,15\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,1\\b=0,05\end{matrix}\right.\\ \Rightarrow\%m_{Cu}=\dfrac{2,7}{12}.100=22,5\%\\ \%m_{Zn}=\dfrac{0,1.65}{12}.100\approx54,167\%\\ \%m_{Fe}=\dfrac{0,05.56}{12}.100\approx23,333\%\)
\(b,ddA:FeCl_2,ZnCl_2,H_2SO_4\left(dư\right)\\ m_{ddH_2SO_4}=200.1,14=228\left(g\right)\\ m_{ddA}=m_{\left(Zn,Fe\right)}+m_{ddH_2SO_4}-m_{H_2}=9,3+228-0,15.2=237\left(g\right)\)
\(C\%_{ddZnCl_2}=\dfrac{136.0,1}{237}.100\approx5,738\%\\ C\%_{ddFeCl_2}=\dfrac{127.0,05}{237}.100\approx2,679\%\\ C\%_{ddH_2SO_4\left(dư\right)}=\dfrac{\left(0,4-0,15\right).98}{237}.100\approx10,338\%\)
Đã sửa lần cuối lúc 20:45
a, PT: \(Zn+2HCl\rightarrow ZnCl_2+H_2\)
\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)
Gọi: \(\left\{{}\begin{matrix}n_{Zn}=x\left(mol\right)\\n_{Al}=y\left(mol\right)\end{matrix}\right.\) ⇒ 65x + 27y = 17,05 (1)
Ta có: \(n_{H_2}=\dfrac{9,52}{22,4}=0,425\left(mol\right)\)
Theo PT: \(n_{H_2}=n_{Zn}+\dfrac{3}{2}n_{Al}=x+\dfrac{3}{2}y=0,425\left(2\right)\)
Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}n_{Zn}=0,2\left(mol\right)\\n_{Al}=0,15\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}m_{Zn}=0,2.65=13\left(g\right)\\m_{Al}=0,15.27=4,05\left(g\right)\end{matrix}\right.\)
b, Theo PT: \(\left\{{}\begin{matrix}n_{ZnCl_2}=n_{Zn}=0,2\left(mol\right)\\n_{AlCl_3}=n_{Al}=0,15\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}C_{M_{ZnCl_2}}=\dfrac{0,2}{0,5}=0,4\left(M\right)\\C_{M_{AlCl_3}}=\dfrac{0,15}{0,5}=0,3\left(M\right)\end{matrix}\right.\)
c, Ta có: m dd HCl = 1,05.500 = 525 (g)
m dd sau pư = mhh + m dd HCl - mH2 = 541,2 (g)
\(\Rightarrow\left\{{}\begin{matrix}C\%_{ZnCl_2}=\dfrac{0,2.136}{541,2}.100\%\approx5,03\%\\C\%_{AlCl_3}=\dfrac{0,15.133,5}{541,2}.100\%\approx3,7\%\end{matrix}\right.\)
Gọi \(\left\{{}\begin{matrix}n_{Zn}=a\left(mol\right)\\n_{Fe}=b\left(mol\right)\end{matrix}\right.\)
\(n_{H_2}=\dfrac{15,68}{22,4}=0,7\left(mol\right)\\ m_{HCl}=200.27,375\%=54,75\left(g\right)\\ n_{HCl}=\dfrac{54,75}{36,5}=1,5\left(mol\right)\)
PTHH:
Zn + 2HCl ---> ZnCl2 + H2
a ----> 2a --------> a -----> a
Fe + 2HCl ---> FeCl2 + H2
b ---> 2b -------> b ------> b
Hệ pt \(\left\{{}\begin{matrix}65a+56b=43,7\\a+b=0,7\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,5\left(mol\right)\\b=0,2\left(mol\right)\end{matrix}\right.\)
\(\rightarrow\left\{{}\begin{matrix}m_{Zn}=0,5.65=32,5\left(g\right)\\m_{Fe}=0,2.56=11,2\left(g\right)\end{matrix}\right.\)
\(m_{dd}=43,7+200-0,7.2=242,3\left(g\right)\\ \rightarrow\left\{{}\begin{matrix}C\%_{ZnCl_2}=\dfrac{0,5.136}{242,3}=28,06\%\\C\%_{FeCl_2}=\dfrac{0,2.127}{242,3}=10,48\%\\C\%_{HCl\left(dư\right)}=\dfrac{\left(1,5-0,5.2-0,2.2\right).36,5}{242,3}=1,51\%\end{matrix}\right.\)
\(n_{H_2}=\dfrac{15,68}{22,4}=0,7\left(mol\right)\\
pthh:\left\{{}\begin{matrix}Zn+H_2SO_4->ZnSO_4+H_2\\Fe+H_2SO_4->FeSO_{\text{ 4 }}+H_2\end{matrix}\right.\)
gọi số mol Zn là x , số mol Fe là y
=> 65x+56y=43,7
=> a+b=0,7
=>a=0,5 , b =0,2
=> \(m_{Zn}=0,5.65=32,5\\ m_{Fe}=43,7-32,5=11,2\left(G\right)\)
a,Fe + 2HCl → FeCl + H2 (1)
FeO + 2HCl → FeCl + H2O (2)
nH2 = 3,36/ 22,4 = 0,15 ( mol)
Theo (1) nH2 = nFe = 0,15 ( mol)
mFe = 0,15 x 56 = 8.4 (g)
m FeO = 12 - 8,4 = 3,6 (g)
a, \(n_{H_2}=\frac{3,36}{22,4}=0,15\left(mol\right)\)
\(Fe+2HCl->FeCl_2+H_2\left(1\right)\)
\(FeO+2HCl->FeCl_2+H_2O\left(2\right)\)
theo (1) \(n_{Fe}=n_{H_2}=0,15\left(mol\right)\)
=> \(m_{Fe}=0,15.56=8,4\left(g\right)\)
=> \(m_{FeO}=12-8,4=3,6\left(g\right)\)
ta thấy : nFe =nH2 = 0,15
=> mFe =0,15 x 56 = 8,4g
%Fe=8,4/12 x 100 = 70%
=>%FeO = 100 - 70 = 30%
b) BTKLra mdd tìm mct of HCl
c) tìm mdd sau pứ -mH2 nha bạn
a, mchất rắn = mCu = 12,8 (g)
=> mhh (Al, Zn) = 28,5 - 12,8 = 16,7 (g)
\(m_{H_2SO_4}=7,84\%.500=39,2\left(g\right)\\ n_{H_2SO_4}=\dfrac{39,2}{98}=0,4\left(mol\right)\)
Gọi \(\left\{{}\begin{matrix}n_{Al}=a\left(mol\right)\\n_{Zn}=b\left(mol\right)\end{matrix}\right.\left(a,b>0\right)\)
PTHH:
2Al + 3H2SO4 ---> Al2(SO4)3 + 3H2↑
a----->1,5a---------->0,5a-------->1,5a
Zn + H2SO4 ---> ZnSO4 + H2
b---->b------------>b--------->b
mdd (tăng) = mhh (Al, Zn) - mH2 = 27a + 65a - 2.(1,5a - b) = 24a - 63b = 515 - 500 = 15 (g)
=> Hệ pt \(\left\{{}\begin{matrix}27a+65b=15,7\\24a-63b=15\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,1\left(mol\right)\\b=0,2\left(mol\right)\end{matrix}\right.\left(TM\right)\)
\(\Rightarrow\left\{{}\begin{matrix}\%m_{Cu}=\dfrac{12,8}{28,5}.100\%=44,9\%\\\%m_{Al}=\dfrac{0,1.27}{28,5}.100\%=18,9\%\\\%m_{Zn}=100\%-44,9\%-18,9\%=36,2\%\end{matrix}\right.\)
b, \(n_{H_2SO_{4\left(dư\right)}}=0,4-0,1.1,5-0,2=0,05\left(mol\right)\)
\(\Rightarrow\left\{{}\begin{matrix}C\%_{Al_2\left(SO_4\right)_3}=\dfrac{0,05.342}{515}.100\%=3,32\%\\C\%_{ZnSO_4}=\dfrac{0,2.161}{515}.100\%=6,25\%\\C\%_{H_2SO_{4\left(dư\right)}}=\dfrac{0,05.98}{515}.100\%=0,95\%\end{matrix}\right.\)
anh ơi \(24a+63b=15\) mới đúng chứ anh:)
\(m_{dd\left(tăng\right)}=24a+63b\) nữa:)
a, Ta có: \(n_{H_2}=\dfrac{4,48}{22,4}=0,2\left(mol\right)\)
PT: \(M+H_2SO_4\rightarrow MSO_4+H_2\)
Theo PT: \(n_M=n_{H_2}=0,2\left(mol\right)\)
\(\Rightarrow M_M=\dfrac{11,2}{0,2}=56\left(g/mol\right)\)
→ M là Fe.
b, Theo PT: \(n_{FeSO_4}=n_{H_2SO_4\left(pư\right)}=n_{H_2}=0,2\left(mol\right)\)
⇒ nH2SO4 dư = 0,5.1 - 0,2 = 0,3 (mol)
\(\Rightarrow\left\{{}\begin{matrix}C_{M_{H_2SO_4\left(dư\right)}}=\dfrac{0,3}{0,5}=0,6\left(M\right)\\C_{M_{FeSO_4}}=\dfrac{0,2}{0,5}=0,4\left(M\right)\end{matrix}\right.\)
c, Ta có: \(n_{FeSO_4.7H_2O}=n_{FeSO_4}=0,2\left(mol\right)\)
\(\Rightarrow m_{FeSO_4.7H_2O}=0,2.278=55,6\left(g\right)\)
