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Mg+ 2HCl→ MgCl2+ H2
(mol) 0,1 0,2 0,1 0,1
a) \(n_{Mg}=\dfrac{m}{M}=\dfrac{2,4}{24}=0,1\left(mol\right)\)
→\(V_{H_2}=n.22,4=0,1.22,4=2,24\left(lít\right)\)
b) Đổi: 100ml=0,1 lít
\(C_{M_{HCl}}=\dfrac{n}{V}=\dfrac{0,2}{0,1}=2M\)
c) \(m_{MgCl_2}=n.M=0,1.95=9,5\left(g\right)\)
Câu 3 :
\(n_{MgO}=\dfrac{8}{40}=0,2\left(mol\right)\)
1) Pt : \(MgO+2HCl\rightarrow MgCl_2+H_2O|\)
1 2 1 1
0,2 0,4 0,2
\(n_{MgCl2}=\dfrac{0,2.1}{1}=0,2\left(mol\right)\)
⇒ \(m_{MgCl2}=0,2.136=27,2\left(g\right)\)
2) \(n_{HCl}=\dfrac{0,2.2}{1}=0,4\left(mol\right)\)
\(m_{HCl}=0,4.36,5=14,6\left(g\right)\)
\(m_{ddHCl}=\dfrac{14,6.100}{20}=73\left(g\right)\)
Chúc bạn học tốt
Mình xin lỗi bạn nhé , bạn sửa lại giúp mình chỗ :
\(m_{MgCl2}=0,2.95=19\left(g\right)\)
Đổi 300ml = 0,3 lít
Ta có: \(n_{H_2SO_4}=0,3.0,5=0,15\left(mol\right)\)
PTHH: H2SO4 + 2KOH ---> K2SO4 + 2H2O
a. Theo PT: \(n_{KOH}=2.n_{H_2SO_4}=2.0,15=0,3\left(mol\right)\)
\(\Rightarrow V_{dd_{KOH}}=\dfrac{0,3}{0,2}=1,5\left(lít\right)\)
b. Theo PT: \(n_{K_2SO_4}=n_{H_2SO_4}=0,15\left(mol\right)\)
\(\Rightarrow m_{K_2SO_4}=0,15.174=26,1\left(g\right)\)
c. Ta có: \(V_{dd_{K_2SO_4}}=V_{dd_{H_2SO_4}}=0,3\left(lít\right)\)
\(\Rightarrow C_{M_{K_2SO_4}}=\dfrac{0,15}{0,3}=0,5M\)
Bài 14:
Ta có: \(n_{BaCO_3}=\dfrac{39,4}{197}=0,2\left(mol\right)\)
PT: \(BaCO_3+2HCl\rightarrow BaCl_2+CO_2+H_2O\)
a, \(n_{CO_2}=n_{BaCO_3}=0,2\left(mol\right)\Rightarrow V_{CO_2}=0,2.24,79=4,958\left(l\right)\)
b, Sửa đề: tính khối lượng dung dịch HCl → tính nồng độ % dd HCl.
\(n_{HCl}=2n_{BaCO_3}=0,4\left(mol\right)\Rightarrow m_{ddHCl}=\dfrac{0,4.36,5}{100}.100\%=14,6\%\)
c, \(n_{BaCl_2}=n_{BaCO_3}=0,2\left(mol\right)\)
Ta có: m dd sau pư = 39,4 + 100 - 0,2.44 = 130,6 (g)
\(\Rightarrow C\%_{BaCl_2}=\dfrac{0,2.208}{130,6}.100\%\approx31,85\%\)
Bài 12:
Ta có: \(n_{MgCO_3}=\dfrac{25,2}{84}=0,3\left(mol\right)\)
PT: \(MgCO_3+2HCl\rightarrow MgCl_2+CO_2+H_2O\)
a, Theo PT: \(n_{CO_2}=n_{MgCO_3}=0,3\left(mol\right)\)
\(\Rightarrow V_{CO_2}=0,3.24,79=7,437\left(l\right)\)
b, Ta có: m dd sau pư = 25,2 + 200 - 0,3.44 = 212 (g)
Theo PT: \(n_{MgCl_2}=n_{MgCO_3}=0,3\left(mol\right)\)
\(\Rightarrow C\%_{MgCl_2}=\dfrac{0,3.95}{212}.100\%\approx13,44\%\)
Bài 13:
Ta có: \(n_{CaCO_3}=\dfrac{10}{100}=0,1\left(mol\right)\)
PT: \(CaCO_3+2HCl\rightarrow CaCl_2+CO_2+H_2O\)
1. \(n_{CO_2}=n_{CaCO_3}=0,1\left(mol\right)\) \(\Rightarrow V_{CO_2}=0,1.24,79=2,479\left(l\right)\)
2. \(n_{HCl}=2n_{CaCO_3}=0,2\left(mol\right)\Rightarrow m_{ddHCl}=\dfrac{0,2.36,5}{7,3\%}=100\left(g\right)\)
3. Ta có: m dd sau pư = 10 + 100 - 0,1.44 = 105,6 (g)
Theo PT: \(n_{CaCl_2}=n_{CaCO_3}=0,1\left(mol\right)\)
\(\Rightarrow C\%_{CaCl_2}=\dfrac{0,1.111}{105,6}.100\%\approx10,51\%\)
a)
$n_{Al} = 0,3(mol)$
$2Al + 3H_2SO_4 \to Al_2(SO_4)_3 + 3H_2$
Theo PTHH :
$n_{H_2SO_4} = \dfrac{3}{2}n_{Al} = 0,45(mol)$
$m_{dd\ H_2SO_4} = \dfrac{0,45.98}{12,25\%} = 360(gam)$
b)
$n_{H_2} = n_{H_2SO_4} = 0,45(mol)$
$V_{H_2} = 0,45.22,4 = 10,08(lít)$
c)
$n_{Al_2(SO_4)_3} = 0,15(mol)$
$m_{dd\ sau\ pư} = 8,1 + 360 - 0,45.2 = 367,2(gam)$
$C\%_{Al_2(SO_4)_3} = \dfrac{0,15.342}{367,2}.100\% = 14\%$
\(n_{Mg}=\dfrac{2,4}{24}=0,1\left(mol\right)\)
PTHH :
\(Mg+H_2SO_4\rightarrow MgSO_4+H_2\uparrow\)
0,1 0,1 0,1 0,1
\(a,m_{MgSO_4}=0,1.120=12\left(g\right)\)
\(b,V_{H_2}=0,1.22,4=2,24\left(l\right)\)
\(c,m_{ddH_2SO_4}=\dfrac{0,1.98.100}{10}=98\left(g\right)\)
\(n_{Mg}=\dfrac{4,8}{24}=0,2\left(mol\right)\\ Mg+H_2SO_4\rightarrow MgSO_4+H_2\\ n_{MgSO_4}=n_{H_2}=n_{H_2SO_4}=n_{Mg}=0,2\left(mol\right)\\ a,m_{MgSO_4}=120.0,2=24\left(g\right)\\ b,V_{H_2\left(đkc\right)}=24,79.0,2=4,958\left(l\right)\\ c,Oxide:A_2O_x\left(x:hoá.trị.A\right)\\ A_2O_x+xH_2SO_4\rightarrow A_2\left(SO_4\right)_x+xH_2O\\ n_{Oxide}=\dfrac{\dfrac{3}{4}.0,2.1}{x}=\dfrac{0,15}{x}\left(mol\right)\\ M_{A_2O_x}=\dfrac{8}{\dfrac{0,15}{x}}=\dfrac{160}{3}x\)
Xét x=1;x=2;x=3;x=8/3 thấy x=3 (TM) khi đó KLR oxide là 160g/mol
\(M_{M_2O_3}=2M_M+3.16=160\left(\dfrac{g}{mol}\right)\\ \Rightarrow M_M=\dfrac{160-48}{2}=56\left(\dfrac{g}{mol}\right)\)
Nên: M là sắt (Fe=56)
Oxide CTHH: Fe2O3
