Đáp án B.

Hướng dẫn :  Phản ứng :

Đáp án C

0,1M

\(H_2SO_4+2NaOH->Na_2SO_4+2H_2O\\ H_2SO_4+Na_2CO_3->Na_2SO_4+CO_2+H_2O\\ n_{Na_2CO_3}=0,1mol=n_{H_2SO_4dư}\\ n_{H_2SO_4}=\dfrac{1}{2}n_{NaOH}=\dfrac{1}{2}.0,15.2=0,15mol\\ C_{M\left(H_2SO_4\right)}=\dfrac{0,15+0,1}{0,25}=1\left(M\right)\\ m_{Na_2SO_4}=142\left(0,15+0,1\right)=35,5g\)

\(n_{SO_3}=\dfrac{20}{80}=0,25\left(mol\right)\\ PTHH:SO_3+H_2O\rightarrow H_2SO_4\\ Mol:0,25\rightarrow0,25\rightarrow0,25\\ C_{MH_2SO_4}=\dfrac{0,25}{0,5}=0,5M\\ Mg+H_2SO_4\rightarrow MgSO_4+H_2\uparrow\\ Mol:0,25\leftarrow0,25\\ m_{Mg}=0,25.24=6\left(g\right)\)

\(Fe^{2+} \to Fe^{3+} + 1e\\ Mn^{+7} + 5e \to Mn^{2+}\\ \Rightarrow n_{Fe^{2+}} = 5n_{KMnO_4} = 0,18.5 =0,9(mol)\\ 2FeCl_3 + Fe \to 3FeCl_2\\ n_{FeCl_3} = \dfrac{2}{3}n_{FeCl_2} = 0,6(mol)\\ n_{Fe\ pư} = \dfrac{1}{3}n_{Fe} = 0,3(mol)\\ \Rightarrow m_{Fe\ trong\ A} = 2,8 + 0,3.56 = 19,6(gam)\\ 2Fe + 3Cl_2 \xrightarrow{t^o} 2FeCl_3\\ n_{Fe} = n_{FeCl_3} = 0,6(mol)\\\)

Phần trăm khối lượng Fe tham gia phản ứng là : \(\dfrac{0,6.56}{0,6.56 + 19,6}.100\% = 63,15\%\)

\(n_{Na_2O}=\dfrac{15,5}{62}=0,25\left(mol\right)\\ PTHH:Na_2O+H_2O\rightarrow2NaOH\\ n_{NaOH}=2.0,25=0,5\left(mol\right)\\ a,C_{MddNaOH}=\dfrac{0,5}{0,5}=1\left(M\right)\\ b,2NaOH+H_2SO_4\rightarrow Na_2SO_4+2H_2O\\ n_{H_2SO_4}=n_{Na_2SO_4}=\dfrac{0,5}{2}=0,25\left(mol\right)\\ m_{H_2SO_4}=0,25.98=24,5\left(g\right)\\ m_{ddH_2SO_4}=\dfrac{24,5.100}{20}=122,5\left(g\right)\\ V_{ddH_2SO_4}=\dfrac{122,5}{1,14}\approx107,456\left(ml\right)\\ c,V_{ddsau}=V_{ddNaOH}+V_{ddH_2SO_4}\approx0,5+0,107456=0,607456\left(l\right)\\C_{MddNa_2SO_4}\approx\dfrac{ 0,25}{0,607456}\approx0,411552\left(M\right)\)

a)

- Xét phần 1:

\(n_{CaCO_3}=\dfrac{10}{100}=0,1\left(mol\right)\)

PTHH: CaCO₃ + 2CH₃COOH --> (CH₃COO)₂Ca + CO₂ + H₂O

               0,1----->0,2

=> \(n_{CH_3COOH\left(P1\right)}=0,2\left(mol\right)\)

- Xét phần 2:

\(n_{H_2}=\dfrac{0,224}{22,4}=0,01\left(mol\right)\)

PTHH: Mg + 2CH₃COOH --> (CH₃COO)₂Mg + H₂

                           0,02<---------------------0,01

=> \(n_{CH_3COOH\left(P2\right)}=0,02\left(mol\right)\)

=> \(n_{CH_3COOH\left(tổng\right)}=0,2+0,02=0,22\left(mol\right)\)

=> \(m_{CH_3COOH\left(tổng\right)}=60.0,22=13,2\left(g\right)\)

b) 

\(n_{CH_3COOH\left(pư\right)}=\dfrac{0,22.75}{100}=0,165\left(mol\right)\)

PTHH: CH₃COOH + C₂H₅OH --H₂SO_4(đ)t^o--> CH₃COOC₂H₅ + H₂O

                 0,165------------------------------>0,165

=> \(m_{CH_3COOC_2H_5}=0,165.88=14,52\left(g\right)\)

c)

\(n_{H_2}=\dfrac{34,944}{22,4}=1,56\left(mol\right)\)

PTHH: 2CH₃COOH + 2Na --> 2CH₃COONa + H₂

                 0,22------------------------------->0,11

           2H₂O + 2Na --> 2NaOH + H₂

             2,9<------------------1,45

=> m_dd = 13,2 + 2,9.18 = 65,4 (g)

=> \(V=\dfrac{65,4}{1,02}=\dfrac{1090}{17}\left(ml\right)\)

\(x=C_{M\left(A\right)}=\dfrac{0,22}{\dfrac{1,09}{17}}=\dfrac{374}{109}M\)

a.\(n_{\left(CH_3COO\right)_2Mg}=\dfrac{14,2}{142}=0,1mol\)

\(2CH_3COOH+Mg\rightarrow\left(CH_3COO\right)_2Mg+H_2\)

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

\(C_{M_{CH_3COOH}}=\dfrac{0,2}{0,25}=0,8M\)

\(V_{H_2}=0,1.22,4=2,24l\)

b.\(NaOH+CH_3COOH\rightarrow CH_3COONa+H_2O\)

      0,2               0,2                                               ( mol )

\(V_{NaOH}=\dfrac{0,2}{0,5}=0,4l\)

\(n_{\left(CH_3COO\right)_2Mg}=\dfrac{14,2}{142}=0,1\left(mol\right)\)

PTHH: 2CH₃COOH + Mg ---> (CH₃COO)₂Mg + H₂

              0,2<---------------------------0,1---------->0,1

=> \(\left\{{}\begin{matrix}C_{M\left(CH_3COOH\right)}=\dfrac{0,2}{0,25}=0,8M\\V_{H_2}=0,1.22,4=2,4\left(l\right)\end{matrix}\right.\)

PTHH: CH₃COOH + NaOH ---> CH₃COONa + H₂O

           0,2------------->0,2

=> \(V_{ddNaOH}=\dfrac{0,2}{0,5}=0,4\left(l\right)\)