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

b+c) Ta có: \(n_{Fe}=\dfrac{16,8}{56}=0,3\left(mol\right)\)

\(\Rightarrow\left\{{}\begin{matrix}n_{H_2}=0,3\left(mol\right)\\n_{HCl}=0,6\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{HCl}=0,6\cdot36,5=21,9\left(g\right)\\V_{H_2}=0,3\cdot22,4=6,72\left(l\right)\end{matrix}\right.\)

d) PTHH: \(NaOH+HCl\rightarrow NaCl+H_2O\)

Ta có: \(\left\{{}\begin{matrix}n_{HCl}=0,6\left(mol\right)\\n_{NaOH}=\dfrac{20}{40}=0,5\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\) HCl còn dư, NaOH p/ứ hết

\(\Rightarrow\) Dung dịch sau p/ứ làm quỳ tím hóa đỏ

Theo PTHH: \(\left\{{}\begin{matrix}n_{NaCl}=0,5\left(mol\right)\\n_{HCl\left(dư\right)}=0,1\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{NaCl}=0,5\cdot58,5=29,25\left(g\right)\\m_{HCl\left(dư\right)}=0,1\cdot36,5=3,65\left(g\right)\end{matrix}\right.\)

Mặt khác: \(m_{dd}=m_{ddHCl}+m_{NaOH}=\dfrac{0,6\cdot36,5}{5\%}+20=458\left(g\right)\)

\(\Rightarrow\left\{{}\begin{matrix}C\%_{NaCl}=\dfrac{29,25}{458}\cdot100\%\approx6,39\%\\C\%_{HCl\left(dư\right)}=\dfrac{3,65}{458}\cdot100\%\approx0,8\%\end{matrix}\right.\)

\(n_{FeCl_3}=\dfrac{48,75}{162,5}=0,3(mol)\\ 3NaOH+FeCl_3\to Fe(OH)_3\downarrow+3NaCl\\ \Rightarrow n_{Fe(OH)_3}=0,3(mol);n_{NaOH}=n_{NaCl}=0,9(mol)\\ a,m_{Fe(OH)_3}=0,3.107=32,1(g)\\ b,m_{dd_{NaOH}}=\dfrac{0,9.40}{10\%}=360(g)\\ c,C\%_{NaCl}=\dfrac{0,9.58,5}{360+48,75-32,1}.100\%=13,98\%\\ \)

\(d,2Fe(OH)_3+3H_2SO_4\to Fe_2(SO_4)_3+6H_2O\\ \Rightarrow n_{H_2SO_4}=0,45(mol)\\ \Rightarrow m_{dd_{H_2SO_4}}=\dfrac{0,45.98}{20\%}=220,5(g)\\ \Rightarrow V_{dd_{H_2SO_4}}=\dfrac{220,5}{1,14}=193,42(ml)\)

\(n_{NaOH}=0.4\cdot1.5=0.6\left(mol\right)\)

\(2NaOH+H_2SO_4\rightarrow Na_2SO_4+H_{2O}\)

\(0.6...........0.3......................0.3\)

\(V_{dd_{H_2SO_4}}=\dfrac{0.3}{1.5}=0.2\left(l\right)\)

\(C_{M_{Na_2SO_4}}=\dfrac{0.3}{0.4+0.2}=0.5\left(M\right)\)

a. PTHH: \(CuSO_4+2NaOH--->Na_2SO_4+Cu\left(OH\right)_2\downarrow\)

b. Đổi 100ml = 0,1 lít

Ta có: \(n_{Cu\left(OH\right)_2}=\dfrac{9,8}{98}=0,1\left(mol\right)\)

Theo PT: \(n_{CuSO_4}=n_{Cu\left(OH\right)_2}=0,1\left(mol\right)\)

=> \(m_{CuSO_4}=0,1.160=16\left(g\right)\)

c. Theo PT: \(n_{NaOH}=2.n_{CuSO_4}=2.0,1=0,2\left(mol\right)\)

=> \(C_{M_{NaOH}}=\dfrac{0,2}{0,1}=2M\)

a) NaOH + HCl --> NaCl + H2O

b) Số mol NaOH là: n(NaOH) = 0,15mol

Theo pthh thì số mol NaCl là: n(NaCl) = 0,15mol

Khối lượng NaCl là: 0,15.58,5 = 8,775g

c)theo pthh thì số mol HCl là: 0,15mol

V(ddHCl)=100ml=0,1l

Nồng độ mol ddHCl là:

0,15/0,1=1,5M

\(a)n_{H_2SO_4}=0,15.1=0,15mol\\ 2NaOH+H_2SO_4\rightarrow Na_2SO_4+2H_2O\)

0,3                 0,15            0,15              0,15

\(C_{M\left(NaOH\right)}=\dfrac{0,3}{0,1}=3M\\ b)C_{M\left(Na_2SO_4\right)}=\dfrac{0,15}{0,1+0,15}=0,6M\)

a,\(n_{CuO}=\dfrac{20}{80}=0,25\left(mol\right)\)

PTHH: CuO + H₂SO₄ →CuSO₄ + H₂O

Mol:     0,25      0,25         0,25

\(m_{ddH_2SO_4}=\dfrac{0,25.98.100}{19,6}=125\left(g\right)\)

b,m_{dd sau pứ} = 20+125 = 145 (g)

\(C\%_{ddCuSO_4}=\dfrac{0,25.160.100\%}{145}=27,59\%\)

\(Cu+H_2SO_4\rightarrow CuSO_4+H_2\)
0,3125    0,3125   0,3125        (mol)
a)\(n_{Cu}=\dfrac{20}{64}=0,3125\left(mol\right)\)
\(m_{H_2SO_4}=0,3125.98=30,625\left(g\right)\)
\(m_{ddH_2SO_4}=\dfrac{30,625}{19,6}.100=156,25\left(g\right)\)
b)\(m_{CuSO_4}=0,3125.160=50\left(g\right)\)
\(m_{ddCuSO_4}=20+156,25=176,25\left(g\right)\)
\(C\%_{CuSO_4}=\dfrac{50}{176,25}.100\approx28,37\%\)

\(n_{CuO}=\dfrac{20}{80}=0,25\left(mol\right)\\ CuO+H_2SO_4\rightarrow CuSO_4+H_2O\\ a.0,25.........0,25..........0,25.......0,25\left(mol\right)\\ Đặt:a=m_{ddH_2SO_4}\left(g\right)\Rightarrow m_{ddX}=a+20\left(g\right)\\Vì.axit.dư\Rightarrow m_{CuSO_4}=0,25.160=40\left(g\right)\\ \dfrac{40}{a+20}.100\%=16\%\Leftrightarrow a=230\left(g\right)\\ \Rightarrow m_{ddH_2SO_4}=230\left(g\right)\\ b.m_{H_2SO_4\left(dư\right)}=230.19,6\%-0,25.98=20,58\left(g\right)\\ C\%_{ddH_2SO_4\left(dư\right)}=\dfrac{20,58}{230+20}.100=8,232\%\)

Câu 3 : 

\(m_{ct}=\dfrac{10.80}{100}=8\left(g\right)\)

\(n_{NaOH}=\dfrac{8}{40}=0,2\left(mol\right)\)

a) Hiện tượng : Xuất hiện kết tủa trắng

Pt : \(2NaOH+MgSO_4\rightarrow Na_2SO_4+Mg\left(OH\right)_2|\)

           2                1                  1               1

        0,2                0,1               0,1            0,1

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

⇒ \(m_{Mg\left(OH\right)2}=0,1.58=5,8\left(g\right)\)

b) \(n_{MgSO4}=\dfrac{0,2.1}{2}=0,1\left(mol\right)\)

 \(m_{MgSO4}=0,1.120=12\left(g\right)\)

\(m_{ddMgSO}=\dfrac{12.100}{10}=120\left(g\right)\)

c) \(n_{Na2SO4}=\dfrac{0,1.1}{1}=0,1\left(mol\right)\)

⇒ \(m_{Na2SO4}=0,1.142=14,2\left(g\right)\)

\(m_{ddspu}=80+120-5,8=194,2\left(g\right)\)

\(C_{Na2SO4}=\dfrac{14,2.100}{194,2}=7,31\)⁰/₀

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Câu 4 : 

\(n_{Fe}=\dfrac{11,2}{56}=0,2\left(mol\right)\)

Pt : \(Fe+H_2SO_4\rightarrow FeSO_4+H_2|\)

         1         1               1           1

        0,2      0,2

\(n_{H2SO4}=\dfrac{0,2.1}{1}=0,2\left(mol\right)\)

\(m_{H2SO4}=0,2.98=19,6\left(g\right)\)

\(m_{ddH2SO4}=\dfrac{19,6.100}{20}=98\left(g\right)\)

\(V_{ddH2SO4}=\dfrac{98}{1,2}\simeq81,67\left(ml\right)\)

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