Gọi số mol của MgO và Zn là a và b

=> 40a + 65b = 34

PTHH: MgO + 2HCl --> MgCl₂ + H₂O

______a------------------->a

Zn + 2HCl --> ZnCl₂ + H₂

b---------------->b

=> 95a + 136b = 73,4

=> a = 0,2; b = 0,4

=> \(\left\{{}\begin{matrix}\%MgO=\dfrac{0,2.40}{34}.100\%=23,529\%\\\%Zn=\dfrac{0,4.65}{34}.100\%=76,471\%\end{matrix}\right.\)

Gọi số mol Al, Ca là a, b

=> 27a + 40b = 8,7

PTHH: 2Al + 6HCl --> 2AlCl₃ + 3H₂

______a------>3a------------->1,5a

Ca + 2HCl --> CaCl₂ + H₂

b--->2b---------------->b

=> m_tăng = 8,7 - m_H2 = 8,1

=> m_H2 = 0,6 (g)

=> \(n_{H_2}=\dfrac{0,6}{2}=0,3\left(mol\right)\)

=> 1,5a + b = 0,3

=> a = 0,1; b = 0,15

=> \(\left\{{}\begin{matrix}\%m_{Al}=\dfrac{0,1.27}{8,7}.100\%=31,03\%\\\%m_{Ca}=\dfrac{0,15.40}{8,7}.100\%=68,97\%\end{matrix}\right.\)

b) n_KOH = 0,3.0,2 = 0,06 (mol)

PTHH: KOH + HCl --> KCl + H₂O

______0,06->0,06

=> n_HCl = 3a + 2b + 0,06 = 0,66(mol)

=> \(V_{ddHCl}=\dfrac{0,66}{0,5}=1,32\left(l\right)\)

Gọi số mol Al, Fe là a, b

=> 27a + 56b = 16,6

PTHH: 2Al + 6HCl --> 2AlCl₃ + 3H₂

______a------------------------>1,5a

Fe + 2HCl --> FeCl₂ + H₂

b------------------------>b

=> m_tăng = 16,6 - m_H2 = 15,6

=> m_H2 = 1 (g)

=> n\(n_{H_2}=\dfrac{1}{2}=0,5\left(mol\right)\)

=> 1,5a + b = 0,5

=> a = 0,2; b = 0,2 

=> \(\left\{{}\begin{matrix}m_{Al}=0,2.27=5,4\left(g\right)\\m_{Fe}=0,2.56=11,2\left(g\right)\end{matrix}\right.\)

28. A

29.C

30.A

31.C

32.C

33.B

34.C

35.B

Al + 3HCl -> AlCl3 + 1,5H2

.x                      x          1,5x   mol

Mg + 2HCl -> MgCl2 + H2

.y                        y          y  mol

Ta có : mhh KL = 27x + 24y = 7,8g

Và : mtăng = mKL – mH2 = 27x + 24y – 2.(1,5x + y) = 7

=> x = 0,2 ; y = 0,1 mol

=> mAl = 5,4g ; mMg  =2,4g

lỗi

C1:

\(m_C=\dfrac{136.88,235}{100}=120\left(g\right)=>n_C=\dfrac{120}{12}=10\left(mol\right)\)

\(m_H=136-120=16\left(g\right)=>n_H=\dfrac{16}{1}=16\left(mol\right)\)

=> CTPT: C₁₀H₁₆

C2:

%H = 100% - 88, 235% = 11,765%

Xét m_C : m_H = 88,235% : 11,765%

=> 12.n_C : n_H = 88,235 : 11,765

=> n_C : n_H = 7,353 : 11,765 = 5 : 8

=> CTPT: (C₅H₈)_n

Mà M = 136

=> n = 2

=> CTPT: C₁₀H₁₆

\(d_{CO_2/kk}=\dfrac{44}{29}=1,517\)

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Bài này em nghĩ vậy thôi, nếu đúng thì chị k cho em nhé. 

1. The homework has been finished ( by me ) 
2. The medicine has been drunk by the cat
3. The clothes have been ironed by the girls 
4. That book has been read ( by me ) 
5. Another glass has been broken by Zack 
6. Four letters have been send ( by me ) 
7. Jane has been known ( by me ) a long time
8. Our team has been won the championship
9. Chinese food has been cooked ( by her ) 
10. A new phone has been bought ( by me ) 
Bài này em nghĩ vậy, nếu chị thấy đúng thì k cho em nhé, còn sai thì thôi ạ