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PTHH: \(MgO+H_2SO_4\rightarrow MgSO_4+H_2O\)
Ta có: \(\left\{{}\begin{matrix}n_{MgO}=\dfrac{40}{40}=1\left(mol\right)\\n_{H_2SO_4}=\dfrac{300\cdot98\%}{98}=3\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\) Axit còn dư
\(\Rightarrow\left\{{}\begin{matrix}n_{MgSO_4}=1\left(mol\right)\\n_{H_2SO_4\left(dư\right)}=2\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}C\%_{MgSO_4}=\dfrac{120}{300+40}\cdot100\%\approx35,3\%\\C\%_{H_2SO_4\left(dư\right)}=\dfrac{2\cdot98}{300+40}\cdot100\%\approx57,65\%\end{matrix}\right.\)
a)\(n_{Fe_2O_3}=0,2\left(mol\right)\)
PT:\(Fe_2O_3+6HCl\rightarrow2FeCl_3+3H_2O\)
\(0,2\) \(1,2\) \(0,4\)
\(\Rightarrow n_{FeCl_3}=0,4\left(mol\right)\)
\(\Rightarrow m_{FeCl_3}=65\left(g\right)\)
b) \(n_{HCl}=\dfrac{218.30\%}{35,5+1}=\dfrac{654}{365}\left(mol\right)\)
Từ PT \(\Rightarrow\)\(n_{HClpư}=1,2\left(mol\right)\)
\(\Rightarrow n_{HCldư}=\dfrac{654}{365}-1,2=\dfrac{216}{365}\left(mol\right)\)
\(\Rightarrow m_{HCldư}=21,6\left(g\right)\)
\(m_{dd}=32+218=250\left(g\right)\)
\(C\%_{FeCl_3}=\dfrac{65}{250}.100\%=26\left(\%\right)\)
\(C\%_{HCldu}=\dfrac{21,6}{250}.100\%=8,64\%\)
nK2O = \(\frac{9,4}{94}=0,1mol\) nCuSO4 = \(\frac{800.10\%}{160}=0,5mol\)
K2O + H2O => 2KOH
0,1-------------->0,2
KOH + CuSO4 => K2SO4 + Cu(OH)2
0,2---> 0,1---------->0,1------>0,1
=> nCuSO4 dư = 0,5-0,1=0,4
mdd = 9,4+800- 0,1. 98 = 799,6 (g)
C% CuSO4 dư= \(\frac{0,1.160}{799,6}.100\%=2\%\)
C% K2SO4 = \(\frac{0,1.174}{799,6}.100\%=2,176\%\)
Ta có: \(n_{Al}=\dfrac{5,4}{27}=0,2\left(mol\right)\)
Ta lại có: \(C_{\%_{H_2SO_4}}=\dfrac{m_{H_2SO_4}}{294}.100\%=20\%\)
=> \(m_{H_2SO_4}=58,8\left(g\right)\)
=> \(n_{H_2SO_4}=\dfrac{58,8}{98}=0,6\left(mol\right)\)
PTHH: 2Al + 3H2SO4 ---> Al2(SO4)3 + 3H2
Ta thấy: \(\dfrac{0,2}{1}=\dfrac{0,6}{3}\)
Vậy không có chất dư.
Theo PT: \(n_{Al_2\left(SO_4\right)_3}=\dfrac{1}{2}.n_{Al}=\dfrac{1}{2}.0,2=0,1\left(mol\right)\)
=> \(m_{Al_2\left(SO_4\right)_3}=0,1.342=34,2\left(g\right)\)
Ta có: \(m_{dd_{Al_2\left(SO_4\right)_3}}=294+5,4-\left(\dfrac{3}{2}.0,2.2\right)=298,8\left(g\right)\)
=> \(C_{\%_{Al_2\left(SO_4\right)_3}}=\dfrac{34,2}{298,8}.100\%=11,45\%\)
PTHH: \(Zn+CuSO_4\rightarrow ZnSO_4+Cu\)
Phản ứng trên là phản ứng thế
Ta có: \(n_{CuSO_4}=\dfrac{32\cdot10\%}{160}=0,02\left(mol\right)=n_{Cu}=n_{Zn}=n_{ZnSO_4}\)
\(\Rightarrow\left\{{}\begin{matrix}m_{Zn}=0,02\cdot65=1,3\left(g\right)\\m_{Cu}=0,02\cdot64=1,28\left(g\right)\\m_{ZnSO_4}=0,02\cdot161=3,22\left(g\right)\\\end{matrix}\right.\) \(\Rightarrow C\%_{ZnSO_4}=\dfrac{3,22}{32+1,3-1,28}\cdot100\%\approx10,06\%\)
\(n_{Fe_2O_3}=\dfrac{32}{160}=0,2\left(mol\right)\)
\(m_{H_2SO_4}=196.40\%=78,4\left(g\right)\Rightarrow n_{H_2SO_4}=\dfrac{78,4}{98}=0,8\left(mol\right)\)
PTHH: Fe2O3 + 3H2SO4 → Fe2(SO4)3 + 3H2O
Mol: 0,2 0,6 0,2
Ta có: \(\dfrac{0,2}{1}< \dfrac{0,8}{3}\) ⇒ Fe2O3 hết, H2SO4 dư
mdd sau pứ = 32 + 196 = 228 (g)
\(C\%_{ddFe_2\left(SO_4\right)_3}=\dfrac{0,2.400.100\%}{228}=35,09\%\)
\(C\%_{ddH_2SO_4dư}=\dfrac{\left(0,8-0,6\right).98.100\%}{228}=8,596\%\)