mBaCl2 = 400.5,2% = 20,8g 
mH2SO4 = 100.1,14.20% = 22,8g 

BaCl2 + H2SO4 = BaSO4 + 2HCl 
208...... 98........... 233........ 2.36,5g 
20,8..... 22,8......... 

20,8/208 < 22,8/98 => BaCl2 phản ứng hết và H2SO4 còn dư 
=> mBaSO4 = 20,8.233/208 = 23,3g 
=> mHCl = 20,8.2.36,5/208 = 7,3g 
=> mH2SO4 (dư) = 22,8 - 20,8.98/208 = 13g 

mdd (trước ph.ư) = 400 + 100.1,14 = 514g 
mdd (sau ph.ư) = 514 - 23,3 = 490,7g 

=> C%HCl = 7,3/490,7 = 1,49% 
=> C%H2SO4 (dư) = 13/490,7 = 2,65% 

Theo đề bài ta có :

\(\left\{{}\begin{matrix}nH2SO4=\dfrac{\left(100.1,14\right).20}{98.100}\approx0,23\left(mol\right)\\nBaCl2=\dfrac{400.5,2}{100.208}=0,1\left(mol\right)\end{matrix}\right.\)

Ta có PTHH :

\(BaCl2+H2SO4->B\text{aS}O4\downarrow+2HCl\)

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

Theo PTHH ta có : \(nBaCl2=\dfrac{0,1}{1}mol< nH2SO4=\dfrac{0,23}{1}mol\)

=> nH2SO4 dư ( tính theo nBaCl2)

a) Ta có : mBaSO4 = 0,1.233=23,3(g)

b) Ta có : \(\left\{{}\begin{matrix}C\%H2SO4\left(d\text{ư}\right)=\dfrac{\left(0,23-0,1\right).98}{100.1,14+400-23,3}.100\%\approx2,596\%\\C\%HCl=\dfrac{0,2.36,5}{100.1,14+400-23,3}.100\%\approx1,49\%\end{matrix}\right.\)

Vậy.......

a, \(H_2SO_4+BaCl_2\rightarrow BaSO_{4\downarrow}+2HCl\)

b, Ta có: \(m_{H_2SO_4}=114.20\%=22,8\left(g\right)\Rightarrow n_{H_2SO_4}=\dfrac{22,8}{96}=0,2375\left(mol\right)\)

\(m_{BaCl_2}=400.5,2\%=20,8\left(g\right)\Rightarrow n_{BaCl_2}=\dfrac{20,8}{208}=0,1\left(mol\right)\)

Xét tỉ lệ: \(\dfrac{0,2375}{1}>\dfrac{0,1}{1}\), ta được H₂SO₄ dư.

Theo PT: \(n_{BaSO_4}=n_{BaCl_2}=0,1\left(mol\right)\Rightarrow m_{BaSO_4}=0,1.233=23,3\left(g\right)\)

c, Theo PT: \(\left\{{}\begin{matrix}n_{H_2SO_4\left(pư\right)}=n_{BaCl_2}=0,1\left(mol\right)\\n_{HCl}=2n_{BaCl_2}=0,2\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow n_{H_2SO_4\left(dư\right)}=0,2375-0,1=0,1375\left(mol\right)\)

Ta có: m _{dd sau pư} = 114 + 400 - 23,3 = 490,7 (g)

\(\Rightarrow\left\{{}\begin{matrix}C\%_{H_2SO_4\left(dư\right)}=\dfrac{0,1375.98}{490,7}.100\%\approx2,75\%\\C\%_{HCl}=\dfrac{0,2.36,5}{490,7}.100\%\approx1,49\%\end{matrix}\right.\)

a) mBaCl₂ = 20,8 g => nBaCl₂ = 0,1 mol

mH₂SO₄ = \(\frac{m_{dd}C\%}{100}\) = \(\frac{100.1,14.20}{100}\) = 22,8 g => nH₂SO₄ ≃ 0,2 mol

BaCl₂ + H₂SO₄➝ BaSO₄↓ + 2HCl

bđ: 0,1 0,2

pứ: 0,1 0,1

dư: 0 0,1

Vậy BaCl₂ hết, H₂SO₄ dư, bài toán tính theo BaCl₂

nBaSO₄ = nBaCl₂ = 0,1 mol

=> mBaSO₄ = 23,3 g

b) nHCl = 2nBaCl₂ = 0,1 mol

=> C_M = 1 M

nH₂SO_4dư = 0,1 mol => C_M = 1 M

BaCl2+H2SO4---->BaSO4+2HCl

n\(_{BaCl2}=\frac{20,8}{208}=0,1\left(mol\right)\)

n\(_{H2SO4}=0,22.1=0,22\left(mol\right)\)

--->H2SO4 duư

Theo pthh

n\(_{BaSO4}=n_{BaCL2}=0,1\left(mol\right)\)

m\(_{BaSO4}=0,1.233=23,3\left(g\right)\)

Theo pthh

n\(_{HCl}=2n_{BaCl2}=0,2\left(mol\right)\)

C\(_{M\left(HCl\right)}=\frac{0,2}{0,22}=0,91M\)

n\(_{H2SO4}dư=0,22-0,1=0,12\left(mol\right)\)

CM\(_{H2SO4}=\frac{0,12}{0,22}=0,55M\)

Ta có : \(\text{n(BaCl2)= 20,8/208= 0,1 (mol)}\)

\(\text{n(H2SO4) = 2,2 (mol)}\)

BaCl2 + H2SO4 -> BaSO4 + 2HCl

Bđ (Mol) 0,1...........2,2

P/u (Mol) 0,1......->.....0,1........->0,1......-> 0,2

Dư (Mol) 0...........2,1

\(\Rightarrow\text{mBaSO4 = 0,1. 233 = 23,3 gam}\)

Sau khi lọc kết tủa dung dịch chứa H2SO4 dư: 2,1 mol và HCl tạo thành: 0,2 mol

CM(H2SO4 dư) = 2,1 : 2,2 = 0,95M

CM(HCl) = 0,2: 2,2 = 0,09 M