a, PT: \(Mg+2HCl\rightarrow MgCl_2+H_2\)

Ta có: \(n_{H_2}=\dfrac{0,672}{22,4}=0,03\left(mol\right)\)

Theo PT: \(n_{Mg}=n_{H_2}=0,03\left(mol\right)\)

\(\Rightarrow m_{Mg}=0,03.24=0,72\left(g\right)\)

\(\Rightarrow\left\{{}\begin{matrix}\%m_{Mg}=\dfrac{0,72}{1,74}.100\%\approx41,38\%\\\%m_{AlCl_3}\approx58,62\%\end{matrix}\right.\)

b, Theo PT: \(n_{HCl}=2n_{H_2}=0,06\left(mol\right)\)

\(\Rightarrow m_{HCl}=0,06.36,5=2,19\left(g\right)\)

\(\Rightarrow C\%_{ddHCl}=\dfrac{2,19}{500}.100\%=0,438\%\)

Bạn tham khảo nhé!

a, nH2 = 0,03 ( mol )

=> nMg = nH2 = 0,03 ( mol )

=> mMg = 0,72 g

=> %Mg \(\approx\) 41,38 % .

=> % Al \(\approx\) 58,62 % .

b, Có : nH2 = 0,03 mol

=> nHCl = nHCl_{từ Al2O3} + nHCl_{từ Mg} = 0,06 + 0,06 = 0,12 ( mol )

=> mHCl = 4,38 ( g )

Lại có : mdd = mhh + mddHCl = 501,74 ( g )

=> \(C\%=\dfrac{m_{HCl}}{m_{dd}}.100\%\approx0,87\%\)

( chắc đoạn trên là Al2O3 :vvvv )

Fe3O4+4H2-to>3Fe+4H2O

                x---------\(\dfrac{3}{4}x\)

CuO+H2-to>Cu+H2O

           y--------y mol

Ta có :

\(\left\{{}\begin{matrix}x+y=0,5\\\dfrac{3}{4}x.56+64y=23,2\end{matrix}\right.\)

=>x=0,4 mol, y=0,1 mol

=>% m Fe3O4=\(\dfrac{0,4.232}{0,4.232+0,1.80}.100\)=92,1%

=>%m CuO=100-92,1=7,9%

\(n_{H_2}=\dfrac{11,2}{22,4}=0,5mol\)

\(Fe_3O_4+4H_2\rightarrow3Fe+4H_2O\)

x             4x          3x

\(CuO+H_2\rightarrow Cu+H_2O\)

y           y          y

\(\Rightarrow\left\{{}\begin{matrix}4x+y=0,5\\3\cdot56x+64y=23,2\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=0,1\\y=0,1\end{matrix}\right.\)

\(\%m_{Fe_2O_3}=\dfrac{0,1\cdot232}{0,1\cdot232+0,1\cdot80}\cdot100\%=74,36\%\)

\(\%m_{CuO}=100\%-74,36\%=25,64\%\)

Chọn B

Gọi a là số mol của CuO và b là số mol của F e 2 O 3 có trong 20 gam

hh 200 ml dd HCl 3,5 M => nHCl = 0,2 . 3,5 = 0,7 mol 

\(m_{CuO}=\dfrac{20.40}{100}=8\left(g\right)\) => \(n_{CuO}=\dfrac{8}{80}=0,1\left(mol\right)\)

\(m_{Fe_2O_3}=\dfrac{60.20}{100}=12\left(g\right)\) => \(n_{Fe_2O_3}=\dfrac{12}{160}=0,075\left(mol\right)\)

PTHH: CuO + H₂ --t^o--> Cu + H₂O

______0,1---------------->0,1

Fe₂O₃ + 3CO --t^o--> 2Fe + 3CO₂

0,075---------------->0,15

=> \(\%Cu=\dfrac{0,1.64}{0,1.64+0,15.56}.100\%=43,243\%\)

a, \(n_{H_2}=\dfrac{8,96}{22,4}=0,4\left(mol\right)\)

PTHH: 2Al + 6HCl → 2AlCl₃ + 3H₂

Mol:      x                                   1,5x

PTHH: Fe + 2HCl → FeCl₂ + H₂

Mol:     y                                   y

b, Ta có hpt: \(\left\{{}\begin{matrix}27x+56y=11\\1,5x+y=0,4\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0,2\\y=0,1\end{matrix}\right.\)

\(\Rightarrow\%m_{Al}=\dfrac{0,2.27.100\%}{11}=49,09\%\Rightarrow\%m_{Fe}=100\%-49,09\%=50,91\%\)

c, \(n_{CuO}=\dfrac{16}{80}=0,2\left(mol\right)\)

Ta có: \(\dfrac{0,2}{1}< \dfrac{0,4}{1}\) ⇒ CuO hết, H₂ dư

PTHH: CuO + H₂ → Cu + H₂O

Mol:      0,2                0,2

\(m_{Cu}=0,2.64=12,8\left(g\right)\)

Gọi \(m_{Al}=a\left(g\right)\left(0< a< 11\right)\)

\(\rightarrow m_{Fe}=11-a\left(g\right)\)

\(\rightarrow\left\{{}\begin{matrix}n_{Al}=\dfrac{a}{27}\left(mol\right)\\n_{Fe}=\dfrac{11-a}{56}\left(mol\right)\end{matrix}\right.\)

PTHH:

\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)

\(\dfrac{a}{27}\)                                       \(\dfrac{a}{18}\)

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

\(\dfrac{11-a}{56}\)                             \(\dfrac{11-a}{56}\)

\(\rightarrow pt:\dfrac{a}{18}+\dfrac{11-a}{56}=0,4\\ \Leftrightarrow m_{Al}=a=5,4\left(g\right)\left(TM\right)\)

\(\rightarrow\left\{{}\begin{matrix}\%m_{Al}=\dfrac{5,4}{11}=49,1\%\\\%m_{Fe}=100\%-49,1\%=50,9\%\end{matrix}\right.\)

\(n_{CuO}=\dfrac{16}{80}=0,2\left(mol\right)\)

PTHH: \(CuO+H_2\underrightarrow{t^o}Cu+H_2O\)

LTL: \(0,2< 0,4\rightarrow\) H₂ dư

\(n_{Cu}=n_{CuO}=0,2\left(mol\right)\rightarrow m_{CuO}=0,2.64=12,8\left(g\right)\)

a. \(n_{H_2}=\dfrac{8.96}{22,4}=0,4\left(mol\right)\)

PTHH : 2Al + 6HCl -> 2AlCl₃ + 3H₂

              \(\dfrac{0.8}{3}\)                             0,4

             Fe + 2HCl -> FeCl₂ + H₂

\(m_{Al}=\dfrac{0,8.27}{3}=7,2\left(g\right)\)

\(m_{Fe}=11-7,2=3,8\left(g\right)\)

b. \(\%m_{Al}=\dfrac{7.2}{11}.100=65,5\%\)

\(\%m_{Fe}=100\%-65,5\%=34,5\%\)

c. \(n_{CuO}=\dfrac{16}{80}=0,2\left(mol\right)\)

PTHH : H₂ + CuO ----t^o----> Cu + H₂O

                      0,2                  0,2

\(m_{Cu}=0,2.64=12,8\left(g\right)\)

\(a,Fe+2HCl\rightarrow FeCl_2+H_2\\ CuO+2HCl\rightarrow CuCl_2+H_2O\\ n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\Rightarrow n_{Fe}=n_{H_2}=0,1\left(mol\right)\\ \Rightarrow\%m_{Fe}=\dfrac{0,1.56}{13,6}.100\%\approx41,176\%\\ \Rightarrow\%m_{CuO}\approx58,824\%\\ b,n_{CuO}=\dfrac{13,6-0,1.56}{80}=0,1\left(mol\right)\\ n_{HCl\left(p.ứ\right)}=2.\left(n_{Fe}+n_{CuO}\right)=2.\left(0,1+0,1\right)=0,4\left(mol\right)\\ \Rightarrow V_{ddHCl}=\dfrac{0,4}{2}=0,2\left(l\right)\)

Đáp án đúng : A