\(n_{Al}=\dfrac{2,7}{27}=0,1mol\)

\(2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\)

0,1       0,15             0 ,05            0,15

a)\(V=0,15\cdot22,4=3,36\left(l\right)\)

b)\(m_{H_2SO_4}=0,15\cdot98=14,7\left(g\right)\)

   \(\Rightarrow m_{ddHCl}=\dfrac{14,7}{9,8}\cdot100=150\left(g\right)\)

c) \(m_{H_2}=0,15\cdot2=0,3\left(g\right)\)

    \(m_{ddsau}=2,7+150-0,3=152,4\left(g\right)\)

    \(m_{Al_2\left(SO_4\right)_3}=0,05\cdot342=17,1\left(g\right)\)

   \(\Rightarrow C\%=\dfrac{17,1}{152,4}\cdot100=11,22\%\)

- Ta có : \(m_{hh}=m_{Na}+m_{Ba}=7,09=23n_{Na}+137n_{Ba}\left(I\right)\)

\(2Na+2H_2O\rightarrow2NaOH+H_2\)

\(Ba+2H_2O\rightarrow Ba\left(OH\right)_2+H_2\)

- Theo PTHH : \(n_{H_2}=\dfrac{V}{22,4}=0,075=\dfrac{1}{2}n_{Na}+n_{Ba}\left(II\right)\)

- Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}n_{Na}=0,07\\n_{Ba}=0,04\end{matrix}\right.\) mol .\(\Rightarrow\left\{{}\begin{matrix}n_{NaOH}=0,07\\n_{Ba\left(OH\right)_2}=0,04\end{matrix}\right.\) mol .

\(\Rightarrow n_{OH^-}=0,15mol\)

Theo bài ra : \(n_{H^+}=0,2V+2.0,15.V=0,5Vmol\)

PT : \(H^++OH^-\rightarrow H_2O\)

Theo PT ion : \(0,5V=0,15\)

\(\Rightarrow V=0,3\left(l\right)\)

- Ta lại có : \(\left\{{}\begin{matrix}n_{Ba\left(OH\right)2}=0,04\\n_{H2SO4}=0,045\end{matrix}\right.\) mol

\(PTHH:Ba\left(OH\right)_2+H_2SO_4\rightarrow BaSO_4+2H_2O\)

Theo PTHH : \(m_{\downarrow}=m_{BaSO4}=0,04.M=9,32\left(g\right)\)

Vậy ...

\(n_{Na}=\dfrac{6,9}{23}=0,3\left(mol\right)\\ 2Na+2H_2O\rightarrow2NaOH+H_2\\ n_{H_2}=\dfrac{0,3}{2}=0,15\left(mol\right)\\ a,V_{H_2\left(đktc\right)}=0,15.22,4=3,36\left(l\right)\\ b,m_{ddsaup.ứ}=m_{Na}+m_{H_2O}-m_{H_2}=6,9+100-0,15.2=106,6\left(g\right)\)

\(n_{Fe}=\dfrac{1,12}{56}=0,02\left(mol\right)\)

\(n_{H2SO4}=0,05.1=0,05\left(mol\right)\)

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

a) Xét tỉ lệ : \(0,02< 0,05\Rightarrow H2SO4dư\)

Theo Pt : \(n_{FeSO4}=n_{H2}=n_{Fe}=0,02\left(mol\right)\)

 \(\Rightarrow V_{H2\left(dktc\right)}=0,02.22,4=0,448\left(l\right)\)

b) \(n_{H2SO4\left(dư\right)}=0,05-0,02=0,03\left(mol\right)\)

\(V_{ddH2SO4\left(dư\right)}=\dfrac{0,03}{1}=0,03\left(l\right)=30\left(ml\right)\)

c) \(C_{MFeSO4}=\dfrac{0,02}{0,05}=0,4\left(M\right)\)

\(C_{MH2SO4\left(dư\right)}=\dfrac{\left(0,05-0,02\right)}{0,05}=0,6\left(M\right)\)

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a,\(n_{Na}=\dfrac{4,6}{23}=0,2\left(mol\right)\)

PTHH: 2Na + 2H₂O → 2NaOH + H₂

Mol:      0,2                      0,2             0,1

\(V_{H_2}=0,1.22,4=2,24\left(l\right)\)

b,\(C_{M_{ddNaOH}}=\dfrac{0,2}{0,5}=0,4M\)

a, \(2Na+2H_2O\rightarrow2NaOH+H_2\)

Ta có: \(n_{Na}=\dfrac{2,3}{23}=0,1\left(mol\right)\)

\(n_{H_2O}=\dfrac{200}{18}=\dfrac{100}{9}\left(mol\right)\)

Xét tỉ lệ: \(\dfrac{0,1}{2}< \dfrac{\dfrac{100}{9}}{2}\), ta được H₂O dư.

Theo PT: \(n_{H_2}=\dfrac{1}{2}n_{Na}=0,05\left(mol\right)\Rightarrow V_{H_2}=0,05.22,4=1,12\left(l\right)\)

b, Theo PT: \(n_{NaOH}=n_{Na}=0,1\left(mol\right)\)

Ta có: m _{dd sau pư} = 2,3 + 100 - 0,05.2 = 102,2 (g)

\(\Rightarrow C\%_{NaOH}=\dfrac{0,1.40}{102,2}.100\%\approx3,91\%\)

c, - Dung dịch làm quỳ tím hóa xanh.

\(n_{Na}=\dfrac{2,3}{23}=0,1\left(mol\right)\\ 2Na+2H_2O\rightarrow2NaOH+H_2\\ n_{H_2}=\dfrac{0,1}{2}=0,05\left(mol\right);n_{NaOH}=n_{Na}=0,1\left(mol\right)\\ a,V=V_{H_2\left(đktc\right)}=0,05.22,4=1,12\left(l\right)\\ b,m_{ddNaOH}=m_{Na}+m_{H_2O}-m_{H_2}=2,3+200-0,05.2=202,2\left(g\right)\\ C\%_{ddNaOH}=\dfrac{40.0,1}{202,2}.100\approx1,978\%\\ c,NaOH-Tính.bazo\Rightarrow Quỳ.tím.hoá.xanh\)

Bài 1: 

PTHH: \(Mg+2HCl\rightarrow MgCl_2+H_2\uparrow\)

Ta có: \(n_{Mg}=\dfrac{4,8}{24}=0,2\left(mol\right)\)

\(\Rightarrow\left\{{}\begin{matrix}n_{HCl}=0,4\left(mol\right)\\n_{H_2}=0,2\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{ddHCl}=\dfrac{0,4\cdot36,5}{14,6\%}=100\left(g\right)\\V_{H_2}=0,2\cdot22,4=4,48\left(l\right)\end{matrix}\right.\)

Bài 2:

PTHH: \(2KOH+H_2SO_4\rightarrow K_2SO_4+2H_2O\)

Ta có: \(\left\{{}\begin{matrix}n_{KOH}=\dfrac{100\cdot11,2\%}{56}=0,2\left(mol\right)\\n_{H_2SO_4}=\dfrac{150\cdot9,8\%}{98}=0,15\left(mol\right)\end{matrix}\right.\)

Xét tỉ lệ: \(\dfrac{0,2}{2}< \dfrac{0,15}{1}\) \(\Rightarrow\) H₂SO₄ còn dư, KOH p/ứ hết

\(\Rightarrow\left\{{}\begin{matrix}n_{K_2SO_4}=0,1\left(mol\right)\\n_{H_2SO_4\left(dư\right)}=0,05\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{K_2SO_4}=0,1\cdot174=17,4\left(g\right)\\m_{H_2SO_4\left(dư\right)}=0,05\cdot98=4,9\left(g\right)\end{matrix}\right.\)

Mặt khác: \(m_{dd}=m_{ddKOH}+m_{ddH_2SO_4}=250\left(g\right)\)

\(\Rightarrow\left\{{}\begin{matrix}C\%_{K_2SO_4}=\dfrac{17,4}{250}\cdot100\%=6,96\%\\C\%_{H_2SO_4\left(dư\right)}=\dfrac{4,9}{250}\cdot100\%=1,96\%\end{matrix}\right.\)

\(n_{Fe}=\dfrac{8,4}{56}=0,15\left(mol\right)\)

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

        1           1              1            1

      0,15       0,15                        0,15

\(n_{H2}=\dfrac{0,15.1}{1}=0,15\left(mol\right)\)

\(V_{H2\left(dktc\right)}=0,15.22,4=3,36\left(l\right)\)

\(n_{H2SO4}=\dfrac{0,15.1}{1}=0,15\left(mol\right)\)

300ml = 0,3l

\(C_{MddH2SO4}=\dfrac{0,15}{0,3}=0,5\left(M\right)\)

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