a) $n_{Fe} = \dfrac{11,2}{56} = 0,2(mol)$
$Fe + 2HCl \to FeCl_2 + H_2$
$n_{HCl} =2 n_{Fe} = 0,2.2 = 0,4(mol)$
$C\%_{HCl} = \dfrac{0,4.36,5}{200}.100\% = 7,3\%$

b) $n_{H_2} = n_{FeCl_2} = n_{Fe} = 0,2(mol)

Sau phản ứng, $m_{dd} = 11,2 + 200 - 0,2.2 = 210,8(gam)$
$C\%_{FeCl_2} = \dfrac{0,2.127}{210,8}.100\% = 12,05\%$

\(a,n_{H_2}=\dfrac{1,12}{22,4}=0,05\left(mol\right)\)

PTHH: \(Fe+2HCl\rightarrow FeCl_2+H_2\uparrow\)

          0,05<-0,1<------0,05<---0,05

\(b,m_{Fe}=0,05.56=2,8\left(g\right)\\ c,m_{ddHCl}=\dfrac{0,1.36,5}{14,6\%}=25\left(g\right)\\ m_{dd}=25+2,8-0,05.2=27,7\left(g\right)\\ \rightarrow C\%_{FeCl_2}=\dfrac{0,05.127}{27,7}.100\%=22,92\%\)

\(n_{Fe_2O_3}=\dfrac{8}{160}=0,05\left(mol\right)\)

PTHH: Fe₂O₃ + 3H₂SO₄ --> Fe₂(SO₄)₃ + 3H₂O

______0,05------>0,15--------->0,05

=> m_H2SO4 = 0,15.98 = 14,7(g)

=> \(C\%\left(H_2SO_4\right)=\dfrac{14,7}{100}.100\%=14,7\%\)

\(C\%\left(Fe_2\left(SO_4\right)_3\right)=\dfrac{0,05.400}{8+100}.100\%=18,52\%\)

PTHH: Fe₂(SO₄)₃ + 6NaOH --> 2Fe(OH)₃\(\downarrow\) + 3Na₂SO₄

________0,05----------------------->0,1

=> mFe(OH)₃ = 0,1.107=10,7(g)

Gọi x, y tương ứng là số mol Mg và MgO: 24x + 40y = 8,8.

x + y = nMgCl2 = 28,5/95 = 0,3

Giải hệ thu được: x = 0,2; y = 0,1.

a) %Mg = 24.0,2/8,8 = 54,54%; %MgO = 100 - 54,54 = 45,46%

b) nHCl = 2(x+y) = 0,6 mol; mdd =36,5.0,6.100/14,6 = 150 gam.

c) mdd sau p.ư = 8,8 + 150 - mH2 = 158,8 - 2.0,2 = 158,4 gam.

%MgCl2 = 28,5/158,4 = 17,99%

Bài 9 : 

\(n_{CuO}=\dfrac{4}{80}=0,05\left(mol\right)\)

\(CuO+2HCl\rightarrow CuCl_2+H_2O\)

0,05--->0,1-------->0,05 

a) \(C_{MddHCl}=\dfrac{0,1}{0,1}=1\left(M\right)\)

b) \(m_{CuCl2}=0,05.135=6,75\left(g\right)\)

c) \(C_{MCuCl2}=\dfrac{0,05}{0,1}0,5\left(M\right)\)

Câu 10 : 

\(n_{FeO}=\dfrac{3,6}{72}=0,05\left(mol\right)\)

\(FeO+2HCl\rightarrow FeCl_2+H_2O\)

0,05-->0,1------->0,05

\(m_{ddHCl}=\dfrac{0,1.36,5}{10\%}100\%=36,5\left(g\right)\)

\(m_{ddspu}=3,6+36,5=40,1\left(g\right)\)

\(C\%_{FeCl2}=\dfrac{0,05.127}{40,1}.100\%=15,84\%\)

Câu 10 :

\(n_{FeO}=\dfrac{3,6}{72}=0,05\left(mol\right)\)

PTHH :

\(FeO+2HCl\rightarrow FeCl_2+H_2O\)

0,05      0,1           0,05       0,05

\(m_{ddHCl}=\dfrac{0,1.36,5.100}{10}=36,5\left(g\right)\)

\(C\%_{FeCl_2}=\dfrac{0,05.127}{\left(3,6+36,5\right)}.100\%=15,84\%\)

\(m_{ct}=\dfrac{20.98}{100}=19,6\left(g\right)\)

\(n_{H2SO4}=\dfrac{19,6}{98}=0,2\left(mol\right)\)

Pt : \(CuO+H_2SO_4\rightarrow CuSO_4+H_2O|\)

         1             1               1             1

        0,2          0,2           0,2

a) \(n_{CuO}=\dfrac{0,2.1}{1}=0,2\left(mol\right)\)

⇒ \(m_{CuO}=0,2.80=16\left(g\right)\)

b) \(n_{CuSO4}=\dfrac{0,2.1}{1}=0,2\left(mol\right)\)

⇒ \(m_{CuSO4}=0,2.160=32\left(g\right)\)

c) \(m_{ddspu}=16+98=114\left(g\right)\)

\(C_{CuSO4}=\dfrac{32.100}{114}=28,7\)⁰/₀

 Chúc bạn học tốt

Ta có: \(n_{CuO}=\dfrac{16}{80}=0,2\left(mol\right)\)

PT: \(CuO+2HCl\rightarrow CuCl_2+H_2O\)

______0,2_____0,4_____0,2 (mol)

a, \(m_{CuCl_2}=0,2.135=27\left(g\right)\)

b, \(m_{HCl}=0,4.36,5=14,6\left(g\right)\Rightarrow C\%_{HCl}=\dfrac{14,6}{300}.100\%\approx4,867\%\)

c, Ta có: m _{dd sau pư} = 16 + 300 = 316 (g)

\(\Rightarrow C\%_{CuCl_2}=\dfrac{27}{316}.100\%\approx8,54\%\)

1) 2Na+2H2O → 2NaOH+H2

2) H2+CuOto→ Cu+H2O

Có nCuO=\(\dfrac{40}{80}\)=0,5 mol

Dựa vào PTHH 2) nH2=nCuO=0,5mol

Dựa vào PTHH 1) nNaOH=2nH2=0,5.2=1moll

Vậy mNaOH=1.40=40

→C%NaOH=\(\dfrac{40}{160}\).100%=25%

Bài 2:

Cho hỗn hợp 2 KL Na và Fe vào H₂O dư thì chỉ có Na pư

2Na + 2H₂O → 2NaOH + H₂

1 <----- 0,5

H₂ + CuO ---> Cu + H₂O

0,5 <-- 0,5

m_NaOH = 1 × 40 = 40 g

=> C% NaOH = m_ct/ m_dd ×100

= 40/160×100 = 25%

Bài 6:

\(n_{Fe\left(OH\right)_3}=\dfrac{21,4}{107}=0,2\left(mol\right)\)

PT: \(Fe\left(OH\right)_3+3HCl\rightarrow FeCl_3+3H_2O\)

_______0,2________0,6______0,2 (mol)

a, \(C\%_{HCl}=\dfrac{0,6.36,5}{200}.100\%=10,95\%\)

b, \(C\%_{FeCl_3}=\dfrac{0,2.162,5}{21,4+200}.100\%\approx14,68\%\)

Bài 7:

\(m_{H_2SO_4}=100.9,8\%=9,8\left(g\right)\Rightarrow n_{H_2SO_4}=\dfrac{9,8}{98}=0,1\left(mol\right)\)

PT: \(ZnO+H_2SO_4\rightarrow ZnSO_4+H_2O\)

______0,1______0,1_______0,1 (mol)

a, \(m_{ZnO}=0,1.81=8,1\left(g\right)\)

b, \(C\%_{ZnSO_4}=\dfrac{0,1.161}{8,1+100}.100\%\approx14,89\%\)