a) Chất rắn Z là Cu.

b)\(n_{Fe}=\dfrac{12-6,4}{56}=0,1mol\)

\(Fe+2HCl\rightarrow FeCl_2+H_2\)

0,1         0,2          0,1          0,1

\(V_{H_2\left(đkc\right)}=0,1.24,79=2,479l\\ m_{FeCl_2}=0,1.127=12,7g\)

Nhóm SO₃ có hóa trị II.

htri II

\(n_{CuO}=\dfrac{1,6}{80}=0,02\left(mol\right)\)

\(n_{H_2SO_4}=\dfrac{100.20\%}{98}=\dfrac{10}{49}\left(mol\right)\)

PTHH :

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

0,02       0,02           0,02       0,02 

\(\dfrac{0,02}{1}< \dfrac{\dfrac{10}{49}}{1}\) ---> H2SO4 dư và tính theo CuO 

\(C\%_{CuSO_4}=\dfrac{0,02.160}{1,6+100}.100\%\approx3,15\%\)

\(C\%_{H_2SO_4dư}=\dfrac{\left(\dfrac{10}{49}-0,02\right).98}{100+1,6}\approx17,76\left(\%\right)\)

Trong dd sau pư chỉ có Ba(OH)₂ dư còn BaCO₃ bị kết tủa rồi nhé.

\(n_{CO_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)

\(n_{Ba\left(OH\right)_2}=0,1.3=0,3\left(mol\right)\)

PTHH :

\(CO_2+Ba\left(OH\right)_2\rightarrow BaCO_3+H_2O\)

0,1           0,1              0,1          0,1 

\(\dfrac{0,1}{1}< \dfrac{0,3}{1}\) ---> Ba(OH)2 dư , tính theo CO2 

\(C_{M\left(BaCO_3\right)}=\dfrac{0,1}{0,1}=1\left(M\right)\)

\(C_{M\left(Ba\left(OH\right)_2\right)dư}=\dfrac{0,3-0,1}{0,1}=2\left(M\right)\)

Ta có: \(n_{MgO}=\dfrac{20}{40}=0,5\left(mol\right)\)

PT: \(MgO+2HCl\rightarrow MgCl_2+H_2O\)

_____0,5______1______0,5 (mol)

a, \(m_{HCl}=1.36,5=36,5\left(g\right)\Rightarrow m_{ddHCl}=\dfrac{36,5}{10\%}=365\left(g\right)\)

b, Ta có: m _{dd sau pư} = 20 + 365 = 385 (g)

\(\Rightarrow C\%_{MgCl_2}=\dfrac{0,5.95}{385}.100\%\approx12,34\%\)

\(n_{MgO}=\dfrac{20}{80}=0,25\left(mol\right)\)

PTHH :

\(MgO+2HCl\rightarrow MgCl_2+H_2O\)

0,25        0,5          0,25        0,25 

\(a,m_{ddHCl}\dfrac{\left(0,5.36,5\right).100}{10}=182,5\left(g\right)\)

\(b,m_{MgCl_2}=0,25.95=23,75\left(g\right)\)

\(m_{ddMgCl_2}=20+182,5=202,5\left(g\right)\)

\(C\%_{MgCl_2}=\dfrac{23,75}{202,5}.100\%=11,73\left(\%\right)\)

\(n_{SO_2}=\dfrac{3,36}{22,4}=0,15\left(mol\right)\)

PTHH :

\(SO_2+Ca\left(OH\right)_2\rightarrow CaSO_3+H_2O\)

0,15      0,15               0,15        0,15 

\(a,V_{Ca\left(OH\right)_2}=\dfrac{0,15}{2}=0,075\left(l\right)\)

\(b,C_{M\left(CaSO_3\right)}=\dfrac{0,15}{0,075}=2\left(M\right)\)

CaSO₃ kết tủa nên sau pư dd thu được chỉ còn nước thôi nhé.

\(n_{P_2O_5}=\dfrac{28,4}{142}=0,2\left(mol\right)\)

PTHH :

\(P_2O_5+3H_2O\rightarrow2H_3PO_4\)

0,2         0,6           0,4 

\(C_{M\left(H_3PO_4\right)}=\dfrac{0,4}{0,3}=\dfrac{4}{3}\left(M\right)\)

Ta có: \(n_{Ba\left(OH\right)_2}=0,5.1=0,5\left(mol\right)\)

\(n_{KOH}=0,5.2=1\left(mol\right)\)

\(n_{BaCO_3}=\dfrac{39,4}{197}=0,2\left(mol\right)\)

TH1: Kết tủa chưa bị hòa tan.

PT: \(CO_2+Ba\left(OH\right)_2\rightarrow BaCO_3+H_2O\)

_____0,2_________________0,2 (mol)

\(\Rightarrow V_{CO_2}=0,2.22,4=4,48\left(l\right)\)

TH2: Kết tủa đã bị hòa tan 1 phần.

PT: \(CO_2+Ba\left(OH\right)_2\rightarrow BaCO_3+H_2O\)

_____0,5______0,5________0,5 (mol)

\(CO_2+2KOH\rightarrow K_2CO_3+H_2O\)

0,5________1________0,5 (mol)

\(CO_2+H_2O+K_2CO_3\rightarrow2KHCO_3\)

0,5_____________0,5 (mol)

\(CO_2+BaCO_3+H_2O\rightarrow Ba\left(HCO_3\right)_2\)

0,3________0,3 (mol)

\(\Rightarrow V_{CO_2}=\left(0,5+0,5+0,5+0,3\right).22,4=40,32\left(l\right)\)

\(n_{Ba\left(OH\right)_2}=0,5.1=0,5\left(mol\right)\)

\(n_{KOH}=2.0,5=1\left(mol\right)\)

\(n_{Ba_2CO_3}=\dfrac{39,4}{137}\left(mol\right)\)

PTHH :

\(Ba\left(OH\right)_2+CO_2\rightarrow BaCO_3+H_2O\)

39,4/137     39,4/137    39,4/137

Ba(OH)2 dư nên không phản ứng tiếp .

\(2KOH+CO_2\rightarrow K_2CO_3+H_2O\)

  1             0,5 

\(V_{CO_2}=\left(\dfrac{197}{685}+0,5\right).22,4\approx17,64\left(l\right)\)

\(n_{K_2O}=\dfrac{11,28}{94}=0,12\left(mol\right)\)

PTHH :

\(K_2O+H_2O\rightarrow2KOH\)

0,12                    0,24 

\(m_{KOH}=0,24.56=13,44\left(g\right)\)

\(m_{ddKOH}=11,28+100=111,28\left(g\right)\)

\(C\%=\dfrac{13,44}{111,28}.100\%\approx12,08\%\)