PTHH : `2Na + 2H_2O -> 2NaOH + H_2`

Dung dịch `X` là `NaOH`

Khí không màu là : `H_2`

`a)`

`n_{Na} = (4,6)/(23) = 0,2` `mol`

`n_{H_2} = 1/2 . n_{Na} = 0,1` `mol`

`V_{H_2} = 0,1 . 22,4 = 2,24` `l`

`b)`

`400ml = 0,4l`

`n_{NaOH} = n_{Na} = 0,2` `mol`

`C_{M_(NaOH)} = (0,2)/(0,4) = 0,5` `M`

`c)`

PTHH : `NaOH + HCl -> NaCl + H_2O`

Ta có `n_{NaOH} = 0,2` `mol`

`-> n_{HCl} = n_{NaOH} = 0,2` `mol`

`-> V_{HCl} = (0,2)/(0,5) = 0,4` `l`

a, \(n_{H_2}=\dfrac{4,48}{22,4}=0,2\left(mol\right)\)

PT: \(2Na+2H_2O\rightarrow2NaOH+H_2\)

Theo PT: \(n_{Na}=2n_{H_2}=0,4\left(mol\right)\Rightarrow m_{Na}=0,4.23=9,2\left(g\right)\)

b, \(n_{NaOH}=2n_{H_2}=0,4\left(mol\right)\)

\(\Rightarrow C_{M_{NaOH}}=\dfrac{0,4}{2}=0,2\left(M\right)\)

\(n_{HCl}=0,3.1=0,3\left(mol\right)\\ NaOH+HCl\rightarrow NaCl+H_2O\\ n_{NaOH}=n_{NaCl}=n_{HCl}=0,3\left(mol\right)\\ V_{\text{dd}NaOH}=V=\dfrac{0,3}{2}=0,15\left(l\right)\\ C_{M\text{dd}A}=C_{M\text{dd}NaCl}=\dfrac{0,3}{0,15+0,3}=\dfrac{2}{3}\left(M\right)\)

1)

$n_{Na_2O} = \dfrac{6,2}{62} = 0,1(mol)$
$Na_2O + H_2O \to 2NaOH$
$n_{NaOH} = 2n_{Na_2O} = 0,2(mol)$
$m_{dd} = 6,2 + 193,8 = 200(gam) \Rightarrow C\%_{NaOH} = \dfrac{0,2.40}{200}.100\% = 4\%$

2) 

$n_{K_2O} = \dfrac{23,5}{94} = 0,25(mol)$
$K_2O + H_2O \to 2KOH$
$n_{KOH} = 2n_{K_2O} = 0,5(mol) \Rightarrow C_{M_{KOH}} = \dfrac{0,5}{0,5} = 1M$

3) $n_{Na_2O} = \dfrac{12,4}{62} = 0,2(mol)$
$Na_2O + H_2O \to 2NaOH$
$n_{NaOH} = 2n_{Na_2O} = 0,4(mol)$
$C_{M_{NaOH}} = \dfrac{0,4}{0,5} =0,8M$

4)

$Na_2SO_3 + 2HCl \to 2NaCl +S O_2 + H_2O$
Theo PTHH : 

$n_{SO_2} = n_{Na_2SO_3} = \dfrac{12,6}{126} = 0,1(mol)$
$V_{SO_2} = 0,1.22,4 = 2,24(lít)$

5) $n_{CaO} = \dfrac{5,6}{56} = 0,1(mol)$

$CaO + 2HCl \to CaCl_2 + H_2O$

Theo PTHH : 

$n_{HCl} = 2n_{CaO} = 0,2(mol) \Rightarrow m_{dd\ HCl} = \dfrac{0,2.36,5}{14,6\%} = 50(gam)$

Bài 1 : 

\(n_{Na2O}=\dfrac{6,2}{62}=0,1\left(mol\right)\)

Pt : \(Na_2O+H_2O\rightarrow2NaOH|\)

           1          1              2

          0,1                      0,2

\(n_{NaOH}=\dfrac{0,1.2}{1}=0,2\left(mol\right)\)

⇒ \(m_{NaOH}=0,2.40=8\left(g\right)\)

\(m_{ddspu}=6,2+193,8=200\left(g\right)\)

\(C_{ddNaOH}=\dfrac{8.100}{200}=4\)⁰/₀

 Chúc bạn học tốt

\(n_{Na_2O}=\dfrac{6.2}{62}=0.1\left(mol\right)\)

\(Na_2O+H_2O\rightarrow2NaOH\)

\(0.1........................0.2\)

b) dung dịch NaOH làm quỳ tím hóa xanh 

\(C_{M_{NaOH}}=\dfrac{0.2}{0.5}=0.4\left(M\right)\)

\(n_{Zn}=\dfrac{13}{65}=0,2\left(mol\right)\)

PTHH: Zn + H₂SO₄ --> ZnSO₄ + H₂

_____0,2---->0,2------>0,2----->0,2

V_H2 = 0,2.22,4 = 4,48(l)

\(C_{M\left(ZnSO_4\right)}=\dfrac{0,2}{0,3}=0,667M\)