Cho 24 gam Fe2O3 vào 250gam dung dịch H2SO4 19,6%. Tính khối lượng của muối thu được sau phản ứng?
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(n_{Fe_2O_3}=\dfrac{24}{160}=0,15(mol)\\ n_{H_2SO_4}=\dfrac{250.19,6\%}{100\%.98}=0,5(mol)\\ PTHH:Fe_2O_3+3H_2SO_4\to Fe_2(SO_4)_3+3H_2O\)
Vì \(\dfrac{n_{Fe_2O_3}}{1}<\dfrac{n_{H_2SO_4}}{3}\) nên \(H_2SO_4\) dư
\(\Rightarrow n_{Fe_2(SO_4)_3}=n_{Fe_2O_3}=0,15(mol)\\ \Rightarrow m_{Fe_2(SO_4)_3}=0,15.400=60(g)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 19 :
\(a) n_{Al} = \dfrac{10,8}{27} = 0,4(mol)\\ 2Al + 3H_2SO_4 \to Al_2(SO_4)_3 + 3H_2\\ n_{H_2} = \dfrac{3}{2}n_{Al} = 0,6(mol)\\ V_{H_2} = 0,6.22,4 = 13,44(lít)\\ b) \text{Chất tan : }Al_2(SO_4)_3\\ n_{Al_2(SO_4)_3} = \dfrac{1}{2}n_{Al} = 0,2(mol)\\ m_{Al_2(SO_4)_3} = 0,2.342 = 68,4(gam)\)
Bài 18 :
\(a) n_{HCl} = \dfrac{250.7,3\%}{36,5 } = 0,5(mol)\\ Zn + 2HCl \to ZnCl_2 + H_2\\ n_{H_2} = \dfrac{1}{2}n_{HCl} = 0,25(mol) \Rightarrow V_{H_2} = 0,25.22,4 = 5,6(lít)\\ b) \text{Chất tan : } ZnCl_2\\ n_{ZnCl_2} = n_{H_2} = 0,25(mol)\\ m_{ZnCl_2} = 0,25.136 = 34(gam)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
nH2 = 6.72 / 22.4 = 0.3 (mol)
Mg + H2SO4 => MgSO4 + H2
0.3.......0.3.............0.3........0.3
mMg = 0.3 * 24 = 7.2 (g)
mH2SO4 = 0.3 * 98 = 29.4 (g)
mddH2SO4 = 29.4 * 100 / 19.6 = 150 (g)
mMgSO4 = 0.3 * 120 = 36 (g)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(n_{Fe_2O_3}=\dfrac{48}{160}=0,3(mol)\\ PTHH:Fe_2O_3+3H_2SO_4\to Fe_2(SO_4)_3+3H_2O\\ \Rightarrow n_{H_2SO_4}=3n_{Fe_2O_3}=0,9(mol)\\ \Rightarrow m_{dd_{H_2SO_4}}=\dfrac{0,9.98}{19,6\%}=450(g)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(m_{H_2SO_4}=\dfrac{19,6\cdot20\%}{100\%}=3,92\left(g\right)\\ \Rightarrow n_{H_2SO_4}=\dfrac{3,92}{98}=0,04\left(mol\right)\\ PTHH:H_2SO_4+BaCl_2\rightarrow BaSO_4\downarrow+2HCl\\ \Rightarrow n_{H_2SO_4}=n_{BaCl_2}=n_{BaSO_4}=0,04\left(mol\right)\\ \Rightarrow m_{CT_{BaCl_2}}=0,04\cdot208=8,32\left(g\right)\\ \Rightarrow m_{dd_{BaCl_2}}=\dfrac{8,32\cdot100\%}{12\%}\approx69,3\left(g\right)\\ m_{kết.tủa}=m_{BaSO_4}=0,04\cdot233=9,32\left(g\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(n_{H_2SO_4}=\dfrac{200\cdot19.6\%}{98}=0.4\left(mol\right)\)
\(SO_3+H_2O\rightarrow H_2SO_4\)
\(0.4......................0.4\)
\(m_{SO_3}=0.4\cdot80=32\left(g\right)\)
\(b.\)
\(n_{H_2SO_4}=\dfrac{80\cdot19.6\%}{98}=0.16\left(mol\right)\)
\(MgO+H_2SO_4\rightarrow MgSO_4+H_2O\)
\(0.16..........0.16..............0.16\)
\(m_{MgO}=0.16\cdot40=6.4\left(g\right)\)
\(m_{\text{dung dịch sau phản ứng}}=6.4+80=86.4\left(g\right)\)
\(C\%MgSO_4=\dfrac{0.16\cdot120}{86.4}\cdot100\%=22.22\%\)
a)
$SO_3 + H_2O \to H_2SO_4$
n SO3 = n H2SO4 = 200.19,6%/98 = 0,4(mol)
=> m = 0,4.80 = 32(gam)
b)
$MgO + H_2SO_4 \to MgSO_4 + H_2O$
n MgSO4 = n MgO = n H2SO4 = 80.19,6%/98 = 0,16(mol)
=> m MgO = 0,16.40 = 6,4(gam)
Sau pư, m dd = 6,4 + 80 = 86,4(gam)
=> C% MgSO4 = 0,16.120/86,4 .100% = 22,22%
![](https://rs.olm.vn/images/avt/0.png?1311)
Tóm tắt
\(V_{H_2\left(đktc\right)}=8,96l\\ C_{\%H_2SO_4}=19,6\%\\ a)m_{Zn}=?\\ m_{ddH_2SO_4}=?\\ b)C_{\%ZnSO_4}=?\)
\(a)n_{H_2}=\dfrac{8,96}{22,4}=0,4mol\\ Zn+H_2SO_4\rightarrow ZnSO_4+H_2\)
0,4 0,4 0,4 0,4
\(m_{Zn}=0,4.65=26g\\ m_{ddH_2SO_4}=\dfrac{0,4.98}{19,6}\cdot100=200g\\ b)C_{\%ZnSO_4}=\dfrac{0,4.161}{26+200-0,4.2}\cdot100=28,6\%\)
nFe2O3=\(\dfrac{24}{160}\)=0,15(mol)
nH2SO4=\(\dfrac{250.19,6\%}{100\%.98}\)=0,5(mol)
PTHH:Fe2O3+3H2SO4→Fe2(SO4)3+3H2O
=>H2SO4 dư
⇒nFe2(SO4)3=nFe2O3=0,15(mol)
⇒mFe2(SO4)3=0,15.400=60(g)
\(n_{Fe_2O_3}=\dfrac{24}{160}=0,15\left(mol\right)\\ m_{H_2SO_4}=19,6\%.250=49\left(g\right)\\ \rightarrow n_{H_2SO_4}=\dfrac{49}{98}=0,5\left(mol\right)\)
PTHH: Fe2O3 + 3H2SO4 ---> Fe2(SO4)3 + 3H2O
LTL: \(\dfrac{0,15}{1}< \dfrac{0,5}{3}\rightarrow\) H2SO4 dư
Theo pthh: \(n_{Fe_2\left(SO_4\right)_3}=n_{Fe_2O_3}=0,15\left(mol\right)\)
\(\rightarrow m_{Fe_2\left(SO_4\right)_3}=0,15.400=60\left(g\right)\)