\(n_{HCl}=\dfrac{18.25}{36.5}=0.5\left(mol\right)\)

\(a.Mg+2HCl\rightarrow MgCl_2+H_2\)

\(b.\)

\(n_{Mg}=n_{H_2}=\dfrac{1}{2}\cdot n_{HCl}=\dfrac{1}{2}\cdot0.5=0.25\left(mol\right)\)

\(m_{Mg}=0.25\cdot24=6\left(g\right)\)

\(V_{H_2}=0.25\cdot22.4=5.6\left(l\right)\)

\(c.\)

\(V_{H_2\left(tt\right)}=5.6\cdot90\%=5.04\left(l\right)\)

\(n_{Al}=\dfrac{5,4}{27}=0,2\left(mol\right)\\ a,PTHH:2Al+6HCl\rightarrow2AlCl_3+3H_2\\ n_{AlCl_3}=n_{Al}=0,2\left(mol\right)\\ n_{H_2}=\dfrac{3}{2}.0,2=0,3\left(mol\right)\\ b,m_{AlCl_3}=133,5.0,2=26,7\left(g\right)\\ c,V_{H_2\left(đktc\right)}=0,3.22,4=6,72\left(l\right)\\ d,m_{ddsau}=5,4+120-0,3.2=124,8\left(g\right)\\ C\%_{ddAlCl_3}=\dfrac{26,7}{124,8}.100\approx21,394\%\)

Gọi n_K2O=a, n_MgO=b trong 8g hh

K₂O + H₂SO₄ \(\rightarrow\) K₂SO₄ + H₂O

a            \(\rightarrow\)               a                         (mol)

MgO + H₂SO₄ \(\rightarrow\) MgSO₄ + H₂O

b              \(\rightarrow\)             b                          (mol)

K₂SO₄ + 2NaOH \(\rightarrow\)  Na₂SO₄ + 2KOH

MgSO₄ + 2NaOH \(\rightarrow\) Na₂SO₄ + Mg(OH)₂

b              \(\rightarrow\)                                      b                (mol)

n_Mg(OH)2 = \(\frac{2,9}{58}\) = 0,05 (mol)

\(\Rightarrow\) b = 0,05 (mol)

\(\Rightarrow\) %^mMgO = \(\frac{0,05.40}{8}\) . 100% = 25%

%^mK₂O = 75%

$a\big)2Al+6HCl\to 2AlCl_3+3H_2$

$b\big)$

$n_{Al}=\dfrac{5,4}{27}=0,2(mol)$

Theo PT: $n_{H_2}=\dfrac{3}{2}n_{Al}=0,3(mol)$

$\to V_{H_2(đktc)}=0,3.22,4=6,72(l)$

$c\big)$

Theo PT: $n_{AlCl_3}=n_{Al}=0,2(mol)$

$\to m_{AlCl_3}=0,2.133,5=26,7(g)$

\(n_{Mg}=\dfrac{4,8}{24}=0,2\left(mol\right)\\ a,PTHH:Mg+2CH_3COOH\rightarrow\left(CH_3COO\right)_2Mg+H_2\\ n_{H_2}=n_{\left(CH_3COO\right)_2Mg}=n_{Mg}=0,2\left(mol\right);n_{CH_3COOH}=2.0,2=0,4\left(mol\right)\\ b,V_{H_2\left(đktc\right)}=0,2.22,4=4,48\left(l\right)\\ c,m_{\left(CH_3COO\right)_2Mg}=142.0,2=28,4\left(g\right)\\ d,m_{ddCH_3COOH}=\dfrac{0,4.60.100}{12}=200\left(g\right)\)

a, \(Zn+2HCl\rightarrow ZnCl_2+H_2\)

b, \(n_{Zn}=\dfrac{6,5}{65}=0,1\left(mol\right)\)

Theo PT: \(n_{H_2}=n_{Zn}=0,1\left(mol\right)\Rightarrow V_{H_2}=0,1.22,4=2,24\left(l\right)\)

c, \(n_{CuO}=\dfrac{12}{80}=0,15\left(mol\right)\)

PT: \(CuO+H_2\underrightarrow{t^o}Cu+H_2O\)

Xét tỉ lệ: \(\dfrac{0,15}{1}>\dfrac{0,1}{1}\), ta được CuO dư.

Theo PT: \(n_{Cu}=n_{H_2}=0,1\left(mol\right)\Rightarrow m_{Cu}=0,1.64=6,4\left(g\right)\)

\(n_{CuO}=\dfrac{16}{80}=0.2\left(mol\right)\)

\(CuO+H_2SO_4\rightarrow CuSO_4+H_2O\)

\(0.2........0.2..................0.2\)

\(V_{dd_{H_2SO_4}}=\dfrac{0.2}{1}=0.2\left(l\right)\)

\(m_{CuSO_4}=0.2\cdot160=32\left(g\right)\)

\(Na+H_2O\rightarrow NaOH+\dfrac{1}{2}H_2\)

Bảo toàn khối lượng : 

\(m_{Na}+m_{H_2O}=m_{NaOH}+m_{H_2}\)

\(m_{NaOH}=2.3+100-0.1=102.2\left(g\right)\)

a, \(MgO+H_2SO_4\rightarrow MgSO_4+H_2O\)

b, Ta có: \(m_{H_2SO_4}=200.9,8\%=19,6\left(g\right)\)

\(\Rightarrow n_{H_2SO_4}=\dfrac{19,6}{98}=0,2\left(mol\right)\)

Theo PT: \(n_{MgO}=n_{MgSO_4}=n_{H_2SO_4}=0,2\left(mol\right)\)

\(\Rightarrow m_{MgO}=0,2.40=8\left(g\right)\)

c, Ta có: m _{dd sau pư} = 8 + 200 = 208 (g)

\(\Rightarrow C\%_{MgSO_4}=\dfrac{0,2.120}{208}.100\%\approx11,54\%\)