Bài 1:

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

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

b, Giả sử: \(\left\{{}\begin{matrix}n_{Zn}=x\left(mol\right)\\n_{Al}=y\left(mol\right)\end{matrix}\right.\)

⇒ 65x + 27y = 21,1 (1)

Ta có: \(n_{H_2}=0,65\left(mol\right)\)

Theo PT: \(n_{H_2}=n_{Zn}+\dfrac{3}{2}n_{Al}=x+\dfrac{3}{2}y\left(mol\right)\)

\(\Rightarrow x+\dfrac{3}{2}y=0,65\left(2\right)\)

Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}x=0,2\left(mol\right)\\y=0,3\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}\%m_{Zn}=\dfrac{0,2.65}{21,1}.100\%\approx61,6\text{% }\\\%m_{Al}\approx38,4\%\end{matrix}\right.\)

c, Theo PT: \(\left\{{}\begin{matrix}n_{ZnCl_2}=n_{Zn}=0,2\left(mol\right)\\n_{AlCl_3}=n_{Al}=0,3\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}m_{ZnCl_2}=0,2.136=27,2\left(g\right)\\m_{AlCl_3}=0,3.133,5=40,05\left(g\right)\end{matrix}\right.\)

Bạn tham khảo nhé!

Bài 2: Cu không tác dụng với dd HCl nên cr thu được là Cu.

PT: \(Fe+2HCl\rightarrow FeCl_2+H_2\)

Ta có: \(n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)

Theo PT: \(n_{Fe}=n_{H_2}=0,1\left(mol\right)\)

\(\Rightarrow m_{Fe}=0,1.56=5,6\left(g\right)\)

\(\Rightarrow m_{cr}=m_{Cu}=10-5,6=4,4\left(g\right)\)

Bạn tham khảo nhé!

Bài 3:

PT: \(2Fe+3Cl_2\underrightarrow{t^o}2FeCl_3\)

\(2Al+3Cl_2\underrightarrow{t^o}2AlCl_3\)

a, Giả sử: \(\left\{{}\begin{matrix}n_{Fe}=x\left(mol\right)\\n_{Al}=y\left(mol\right)\end{matrix}\right.\)

⇒ 56x + 27y = 2,2 (1)

Ta có: \(n_{Cl_2}=0,09\left(mol\right)\)

Theo PT: \(n_{Cl_2}=\dfrac{3}{2}n_{Fe}+\dfrac{3}{2}n_{Al}=\dfrac{3}{2}x+\dfrac{3}{2}y\left(mol\right)\)

\(\Rightarrow\dfrac{3}{2}x+\dfrac{3}{2}y=0,09\left(2\right)\)

Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}x=0,02\left(mol\right)\\y=0,04\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}\%m_{Fe}=\dfrac{0,02.56}{2,2}.100\%\approx50,91\%\\\%m_{Al}\approx49,09\%\end{matrix}\right.\)

b, Theo PT: \(\left\{{}\begin{matrix}n_{FeCl_3}=n_{Fe}=0,02\left(mol\right)\\n_{AlCl_3}=n_{Al}=0,04\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}m_{FeCl_3}=0,02.162,5=3,25\left(g\right)\\m_{AlCl_3}=0,04.133,5=5,34\left(g\right)\end{matrix}\right.\)

Bạn tham khảo nhé!

Chọn C.

\(n_{H_2}=0,4mol\)

\(\Rightarrow n_{HCl}=2n_{H_2}=0,8mol\)

\(C_M=\dfrac{0,8}{\dfrac{400}{1000}}=2M\)

c

... 0,54 lít H₂ ở đktc hả bn ?

Đặt : 

nFe = x mol 

nMgO = y mol 

mX = 56x + 40y = 13.6 (g) (1) 

Fe +  2HCl => FeCl2 + H2 

x____________x

MgO + 2HCl => MgCl2 + H2O 

y______________y

mM = mFeCl2 + mMgCl2 = 127x + 95y = 31.7 (2) 

(1) , (2) : 

x = 0.1 

y = 0.2 

%Fe = 5.6/13.6 * 100% = 41.17%

%MgO = 58.82%

nKOH = 0.1 * 0.2 = 0.02 (mol) 

KOH + HCl => KCl + H2O 

0.02____0.02 

nHCl (pư) = 2nFe + 2nMgO = 0.1*2 + 0.2*2 = 0.6 (mol) 

nHCl = 0.02 + 0.6 = 0.62 (mol) 

VddHCl = 0.62/0.5 = 1.24 (M) 

B
C
A

1.B

2.C

3.A

HT

PTHH: 3Fe₃O₄ + 8Al --t^o--> 4Al₂O₃ + 9Fe

=> \(\dfrac{n_{Fe}}{n_{Al_2O_3}}=\dfrac{9}{4}\)

P1: Gọi (n_Al; n_Fe; n_Al2O3) = (a;b;c)

PTHH: 2Al + 2NaOH + 2H₂O --> 2NaAlO₂ + 3H₂

         0,04<---------------------------------0,06

=> a = 0,04 (mol)

Chất rắn không tan là Fe

\(b=\dfrac{20,16}{56}=0,36\left(mol\right)\)

Có: \(\dfrac{n_{Fe}}{n_{Al_2O_3}}=\dfrac{b}{c}=\dfrac{9}{4}\) => c = 0,16 (mol)

P2: Gọi (n_Al; n_Fe; n_Al2O3) = (ak;bk;ck)

PTHH: 2Al + 6HCl --> 2AlCl₃ + 3H₂

            ak------------------>1,5ak

             Fe + 2HCl --> FeCl₂ + H₂

             bk------------------>bk

=> 1,5ak + bk = 0,63

=> k = 1,5

Bảo toàn Fe: \(n_{Fe_3O_4\left(X\right)}=\dfrac{b+bk}{3}=\dfrac{0,36+0,36.1,5}{3}=0,3\left(mol\right)\)

Bảo toàn Al: \(n_{Al\left(X\right)}=a+2c+ak+2ck=0,9\left(mol\right)\)

\(\left\{{}\begin{matrix}\%m_{Fe_3O_4}=\dfrac{0,3.232}{0,3.232+0,9.27}.100\%=74,12\%\\\%m_{Al}=\dfrac{0,9.27}{0,3.232+0,9.27}.100\%=25,88\%\end{matrix}\right.\)