pthh 2Na + 2H2O ---> 2NaOH + H2
nNaOH = 16 : 40 = 0,4 (mol) 
theo pthh , nNa = nNaOH = 0,4(mol) 
=> mNa = 0,4 . 23 = 9,2 (g) 
theo pthh , nH2 = 1/2 nNa = 0,2 (mol) 
=> VH2 = 0,2 . 22,4 = 4,48 (l) 

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

a. PTHH: 2Na + 2H₂O ---> 2NaOH + H₂↑

b. Ta có: \(n_{H_2O}=\dfrac{97,8}{18}=5,43\left(mol\right)\)

Ta thấy: \(\dfrac{0,1}{2}< \dfrac{5,43}{2}\)

=> H₂O dư.

Theo PT: \(n_{H_2}=\dfrac{1}{2}.n_{Na}=\dfrac{1}{2}.0,1=0,05\left(mol\right)\)

=> \(V_{H_2}=0,05.22,4=1,12\left(lít\right)\)

c. Ta có: \(m_{dd_{NaOH}}=2,3+97,8=100,1\left(g\right)\)

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

=> \(m_{NaOH}=0,1.40=4\left(g\right)\)

=> \(C_{\%_{NaOH}}=\dfrac{4}{100,1}.100\%=3,996\%\)

a)

$M + 2HCl \to MCl_2 + H_2$
$n_{HCl} = 0,3.1 = 0,3(mol)$

Theo PTHH : $n_M = \dfrac{1}{2}n_{HCl} = 0,15(mol)$

$\Rightarrow M = \dfrac{3,6}{0,15} = 24(Mg)$

b)

$n_{MgCl_2} = n_{Mg} = 0,15(mol)$
$m_{MgCl_2} = 0,15.95 = 14,25(gam)$

c) $n_{H_2} = n_{Mg} = 0,15(mol)$
$V_{H_2} = 0,15.22,4 = 3,36(lít)$

`Fe + 2HCl -> FeCl_2 + H_2 \uparrow`

 `0,1`      `0,2`          `0,1`       `0,1`         `(mol)`

`n_[Fe]=[5,6]/56=0,1(mol)`

`a)V_[H_2]=0,1.22,4=2,24(l)`

`b)C_[M_[HCl]]=[0,2]/[0,1]=2(M)`

a) 3Zn + 8HNO₃ --> 3Zn(NO₃)₂ + 2NO + 4H₂O

b) \(n_{HNO_3}=0,2.4=0,8\left(mol\right)\)

PTHH: 3Zn + 8HNO₃ --> 3Zn(NO₃)₂ + 2NO + 4H₂O

           0,3<----0,8----------------------->0,2

=> m_Zn = 0,3.65 = 19,5 (g)

c) V_NO = 0,2.22,4 = 4,48(l)

\(n_{AlCl_3}=\dfrac{26.7}{133.5}=0.2\left(mol\right)\)

\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)

\(.........0.6......0.2.......0.3\)

\(V_{H_2}=0.3\cdot22.4=6.72\left(l\right)\)

\(C\%HCl=\dfrac{0.6\cdot36.5}{300}\cdot100\%=7.3\%\)

a) $Zn + H_2SO_4 \to ZnSO_4 + H_2$

b) Theo PTHH :

$n_{H_2} = n_{ZnSO_4} = n_{Zn} = \dfrac{32,5}{65} = 0,5(mol)$

$V_{H_2} = 0,5.22,4 = 11,2(lít)$

$m_{ZnSO_4} = 0,5.161 = 80,5(gam)$

c) 

$n_{H_2SO_4} = n_{Zn} = 0,5(mol)$

$C\%_{H_2SO_4} = \dfrac{0,5.98}{168,5}.100\% = 29,08\%$

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