\(n_{Ca}=\dfrac{8}{40}=0,2mol\\ 2Ca+O_2\xrightarrow[]{t^0}2CaO\\ n_{CaO}=n_{Ca}=0,2mol\\ n_{HCl}=\dfrac{18,25}{36,5}=0,5mol\\ CaO+2HCl\rightarrow CaCl_2+H_2O\\ \Rightarrow\dfrac{0,2}{1}< \dfrac{0,5}{2}\Rightarrow HCl.dư\\ n_{CaCl_2}=n_{CaO}=0,2mol\\ n_{HCl}=2n_{CaO}=0,4mol\\ m_{CaCl_2}=0,2.111=22,2g\\ m_{HCl.dư}=\left(0,5-0,4\right).36,5=3,65g\)

theo bài ta có :

m_BaCl2 = 20,8 g => n_BaCl2 = 0,1mol

m_H2SO4 = 9,8g => n_H2SO4 = 0,1mol

pthh:

BaCl₂ + H₂SO₄ -> BaSO₄ + 2HCl

1mol.....1mol ..........1mol.........2mol.

0,1mol..0,1mol..........0,1mol.....0,2mol

theo pt ta có

n_BaSO4 = 0,1mol => m_BaSO4 = 23,3g

n_HCl = 0,2mol => m_HCl = 7,3g

BaCl₂ + H₂SO₄ → BaSO₄↓ + 2HCl

\(n_{BaCl_2}=\dfrac{20,8}{208}=0,1\left(mol\right)\)

\(n_{H_2SO_4}=\dfrac{9,8}{98}=0,1\left(mol\right)\)

Theo PT: \(n_{BaCl_2}=n_{H_2SO_4}\)

Theo bài: \(n_{BaCl_2}=n_{H_2SO_4}\)

Vì \(1=1\) ⇒ BaCl₂ và H₂SO₄ đều phản ứng hết

Theo PT: \(n_{BaSO_4}=n_{BaCl_2}=0,1\left(mol\right)\)

\(\Rightarrow m_{BaSO_4}=0,1\times233=23,3\left(g\right)\)

Theo PT: \(n_{HCl}=2n_{BaCl_2}=2\times0,1=0,2\left(mol\right)\)

\(\Rightarrow m_{HCl}=0,2\times36,5=7,3\left(g\right)\)

PTHH: BaCl₂ + H₂SO₄ \(\rightarrow\) 2HCl + BaSO₄
n_BaCl2 = \(\dfrac{20,8}{208}\)=0,1 (mol)
n_H2SO4=\(\dfrac{9,8}{98}\)=0,1 (mol)
Ta có tỉ lệ : n_{\(\dfrac{BaCl2}{1}\)=0,1 = n\(\dfrac{H2SO4}{1}\)=0,1}
\(\Rightarrow\) BaCl2 và H2SO4 đều phản ứng hết
Theo PT: n_HCl = 2n_BaCl2 = 2.0,1=0,2(mol)
\(\Rightarrow\) m_HCl = 0,2.26,5 = 7,3 (g)
Theo PT: n_BaSO4 = n_H2SO4 = 0,1(mol)
\(\Rightarrow\)m_BaSO4 = 0,1.233 = 23,3(g)

\(PTHH:CuO+2HCl\rightarrow CuCl_2+H_2O\)

+ \(\dfrac{n_{CuO\left(bđ\right)}}{n_{CuO\left(PTHH\right)}}=\dfrac{0,25}{1}=0,25\)

+ \(\dfrac{n_{HCl\left(bđ\right)}}{n_{HCl\left(PTHH\right)}}=\dfrac{0,5}{2}=0,25\)

=> pư trên vừa đủ

=> \(m_{CuCl_2}=0,25.135=33,75g\)

theo bài ra ta có :

m_CuO = 20g => n_CuO = 0,25mol

m_HCl = 18,25 g => n_HCl = 0,5mol

pthh:

CuO + 2HCl -> CuCl₂ + H₂O

1mol.....2mol.......1mol.......1mol

0,25mol..0,5mol...0,25mol....0,25mol

theo pt ta có n_CuO = \(\dfrac{1}{2}\)n_HCl = n_CuCl2 = n_H2O = 0,25mol

=> m_CuCl2 = n_CuCl2 . M_CuCl2 = 0,25 . 135 = 33,75 g

=> m_H2O = n_H2O . M_H2O = 0,25.18 = 4,5 g

Ta có: n_{CuO = m / M = 20/ (64+16) = 20/80=0,25 (mol)}

_{CuO → Cu →O}

_{⇔ 0,25 → 0,25 →0,25 ^(mol)}

_^=> m_{Cu = 0,25 * 64 =16 (g)}

m_{O = 0,25 * 16 = 4 (g)}

Tương tự ta có : n_HCl = 18,25 / 36,5 =0,5(mol)

HCl → H → Cl

<=>0,5 → 0,5 → 0,5 ^(mol)

=>m_H =0,5 * 1=0,5(g)

m_Cl = 0,5 *35,5 =17,75 (g)

Tk

2Ca + O₂ -> 2CaO (1)

CaO + 2HCl -> CaCl₂ + H₂O (2)

n_Ca=0,4(mol)

n_HCl=0,5(mol)

Từ 1:

n_CaO=n_Ca=0,4(mol)

Vì 1212n_HCl=0,25(mol)

m_CaCl2=111.0,25=27,75(g)

m_CaO=56.0,15=8,4(g)

n_Mg = 4,8/24 = 0,2 mol

n_HCl = 3,65/36,5 = 0,1 mol

PTPƯ: Mg + 2HCl ---> MgCl₂ + H₂

a, Ta có tỉ hệ Mg:HCl = 0,2/1>0,1/2 (Mg dư tính theo HCl)

2 mol HCl ---> 1 mol H₂

0,1 mol HCl ---> 0,05 mol H₂

V_{H2 =} 0,05 . 22,4 = 1,12 (lít)

b, 

2 mol HCl ---> 1 mol MgCl₂

0,1 mol HCl ---> 0,05 mol MgCl₂

mMgCl₂ = 0,05 . 95 = 4,75 (g)

c, Số mol Mg khi ko dư

2 mol HCl ---> 1 mol Mg

0,1 mol HCl ---> 0,05 mol Mg

số g Mg dư là: (0,2-0,05).24= 3,6 (g)

n_Mg = 4,8/24 = 0,2 mol

n_HCl = 3,65/36,5 = 0,1 mol

PTPƯ: Mg + 2HCl ---> MgCl₂ + H₂

a, Ta có tỉ hệ Mg:HCl = 0,2/1>0,1/2 (Mg dư tính theo HCl)

2 mol HCl ---> 1 mol H₂

0,1 mol HCl ---> 0,05 mol H₂

V_{H2 =} 0,05 . 22,4 = 1,12 (lít)

b, 

2 mol HCl ---> 1 mol MgCl₂

0,1 mol HCl ---> 0,05 mol MgCl₂

mMgCl₂ = 0,05 . 95 = 4,75 (g)

c, Số mol Mg khi ko dư

2 mol HCl ---> 1 mol Mg

0,1 mol HCl ---> 0,05 mol Mg

số g Mg dư là: (0,2-0,05).24= 3,6 (g)

\(n_{Zn}=\dfrac{8,125}{65}=0,125\left(mol\right)\\ m_{HCl}=\dfrac{100.18,25}{100}=18,25\left(g\right)\\ n_{HCl}=\dfrac{18,25}{36,5}=0,5\\ pthh:Zn+2HCl\rightarrow ZnCl_2+H_2\uparrow\)  
            0,125                            0,125 (mol ) 
\(\Rightarrow V_{H_2}=0,125.22,4=2,8\left(l\right)\\ \)   
\(C\%=\dfrac{8,125}{8,125+18,25}.100\%=30,8\%\)
 

Bài 18:

Ta có: \(n_{Zn}=\dfrac{8,125}{65}=0,125\left(mol\right)\)

\(m_{HCl}=100.18,25\%=18,25\left(g\right)\Rightarrow n_{HCl}=\dfrac{18,25}{36,5}=0,5\left(mol\right)\)

a, PT: \(Zn+2HCl\rightarrow ZnCl_2+H_2\)

b, Xét tỉ lệ: \(\dfrac{0,125}{1}< \dfrac{0,5}{2}\), ta được HCl dư.

Theo PT: \(n_{H_2}=n_{Zn}=0,125\left(mol\right)\)

\(\Rightarrow V_{H_2}=0,125.22,4=2,8\left(g\right)\)

\(m_{H_2}=0,125.2=0,25\left(g\right)\)

c, Theo PT: \(\left\{{}\begin{matrix}n_{ZnCl_2}=n_{Zn}=0,125\left(mol\right)\\n_{HCl\left(pư\right)}=2n_{Zn}=0,25\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow n_{HCl\left(dư\right)}=0,25\left(mol\right)\)

Có: m _{dd sau pư} = 8,125 + 100 - 0,25 = 107,875 (g)

\(\Rightarrow\left\{{}\begin{matrix}C\%_{ZnCl_2}=\dfrac{0,125.136}{107,875}.100\%\approx15,76\%\\C\%_{HCl\left(dư\right)}=\dfrac{0,25.36,5}{107,875}.100\%\approx8,46\%\end{matrix}\right.\)

Bạn tham khảo nhé!

`a)PTHH:`

`Zn + 2HCl -> ZnCl_2 + H_2↑`

`0,125`  `0,25`    `0,125`    `0,125`      `(mol)`

`b)n_[Zn] = [ 8,125 ] / 65 = 0,125 (mol)`

`n_[HCl] = [ [ 18,25 ] / 100 . 100 ] / [ 36,5 ] = 0,5 (mol)`

Ta có: `[ 0,125 ] / 1 < [ 0,5 ] / 2`

    `-> Zn` hết, `HCl` dư

 `=> V_[H_2] = 0,125 . 22,4 = 2,8 (l)`

 `=> m_[H_2] = 0,125 . 2 = 0,25 (g)`

`c)m_\text{dd sau p/ứ} = 8,125 + 100 - 0,25 = 107,875 (g)`

`=> C%_[ZnCl_2] = [ 0,125 . 136 ] / [ 107,875 ] . 100 ~~ 15,76%`

`=> C%_[HCl(dư)] = [ ( 0,5 - 0,25 ) . 36,5 ] / [ 107,875 ] . 100 ~~ 8,46%`

a. Ta có: \(n_{Fe_3O_4}=\dfrac{23,2}{232}=0,1\left(mol\right)\)

Ta lại có: \(C_{\%_{HCl}}=\dfrac{m_{ct_{HCl}}}{100}.100\%=7,3\%\)

=> m_HCl = 7,3(g)

=> \(n_{HCl}=\dfrac{7,3}{36,5}=0,2\left(mol\right)\)

PTHH:

Fe₃O₄ + 8HCl ---> FeCl₂ + 2FeCl₃ + 4H₂O

    1   --->   8

    0,1 --->  0,2

=> \(\dfrac{0,1}{1}>\dfrac{0,2}{8}\)

Vậy Fe₃O₄ dư

=> m_dư = 23,2 - 7,3 = 15,9 (g)

b. Theo PT: \(n_{FeCl_2}=\dfrac{1}{8}.n_{HCl}=\dfrac{1}{8}.0,2=0,025\left(mol\right)\)

=> \(m_{FeCl_2}=0,025.127=3,175\left(g\right)\)

Theo PT: \(n_{FeCl_3}=\dfrac{1}{4}.n_{HCl}=\dfrac{1}{4}.0,2=0,05\left(mol\right)\)

=> \(m_{FeCl_3}=0,05.162,5=8,125\left(g\right)\)

=> \(m_{muối}=8,125+3,175=11,3\left(g\right)\)

c. Ta có: m_{dung dịch sau PỨ} = \(23,2+100=123,2\left(g\right)\)

Theo PT: \(n_{H_2O}=\dfrac{1}{2}.n_{HCl}=\dfrac{1}{2}.0,2=0,1\left(mol\right)\)

=> \(m_{H_2O}=0,1.18=1,8\left(g\right)\)

m_{các chất sau PỨ} = 1,8 + 11,3 = 13,1(g)

=> \(C_{\%_{sauPỨ}}=\dfrac{13,1}{123,2}.100\%=10,63\%\)