PT: \(CH_4+2O_2\underrightarrow{t^o}CO_2+2H_2O\)

\(C_2H_4+3O_2\underrightarrow{t^o}2CO_2+2H_2O\)

Giả sử: \(\left\{{}\begin{matrix}n_{CH_4}=x\left(mol\right)\\n_{C_2H_4}=y\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow x+y=\dfrac{7,84}{22,4}=0,35\left(1\right)\)

Ta có: \(n_{O_2}=\dfrac{19,04}{22,4}=0,85\left(mol\right)\)

Theo PT: \(n_{O_2}=2n_{CH_4}+3n_{C_2H_4}=2x+3y\)

⇒ 2x + 3y = 0,85 (2)

Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}x=0,2\left(mol\right)\\y=0,15\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}\%m_{CH_4}=\dfrac{0,2.16}{0,2.16+0,15.28}.100\%\approx43,2\%\\\%m_{C_2H_4}\approx56,8\%\end{matrix}\right.\)

Bạn tham khảo nhé!

1)

$CH_4 +2 O_2 \xrightarrow{t^o} CO_2 + 2H_2O$

Theo PTHH : 

$V_{O_2\ cần\ dùng} = 2V_{CH_4} = 24,79(lít)$
$V_{CO_2} = V_{CH_4} = 12,395(lít)$

2)

a)

$C_2H_4 + 3O_2 \xrightarrow{t^o} 2CO_2 + 2H_2O$
$V_{O_2} = 3V_{C_2H_4} = 14,874(lít)$

b) $V_{không\ khí} = V_{O_2} : 20\% = 14,874 : 20\% = 74,37(lít)$

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

\(n_{O_2}=\dfrac{26,88}{22,4}=1,2\left(mol\right)\)

Đặt \(\left\{{}\begin{matrix}n_{CH_4}=x\\n_{C_2H_4}=y\end{matrix}\right.\) ( mol ) \(\Rightarrow n_{hhk}=x+y=0,5\left(1\right)\)

\(CH_4+2O_2\rightarrow\left(t^o\right)CO_2+2H_2O\)

 x          2x                                   ( mol )

\(C_2H_4+3O_2\rightarrow\left(t^o\right)2CO_2+2H_2O\)

  y        3y                                     ( mol )

\(\rightarrow n_{O_2}=2x+3y=1,2\left(2\right)\)

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

\(\%V_{CH_4}=\dfrac{0,3}{0,5}.100=60\%\)

\(\%V_{C_2H_4}=100-60=40\%\)

a) C2H4 + Br2 ---> C2H4Br2

Khí thoát ra là CH4 (metan) ---> mCH4 = 0,2.16 = 3,2g ---> mC2H4 = 6 - 3,2 = 2,8g. (0,1 mol).

---> %CH4 = 0,2/0,3 = 66,7%; %C2H4 = 33,3%.

b) nCO2 = nCH4 + 2nC2H4 = 0,4 mol.

CO2 + Ca(OH)2 ---> CaCO3 + H2O

CO2 + CaCO3 + H2O ---> Ca(HCO3)2

---> nCaCO3 = 0,2 mol ---> m = 0,2.100 = 20g.

nCa(OH)2=0.3=>nCaCO3=0.3 chứ

Đáp án A

Đáp án A

n C O 2 = 7 , 84 22 , 4 = 0 , 35 ( m o l )   ;   n H 2 O   = 9 , 9 18 = 0 , 55 ( m o l )

Bảo toàn nguyên tố O:

2 n O 2 = 2 n C O 2 + n H 2 O   ⇒ n O 2 = 0 , 625 ( m o l )   ⇒ V O 2 = 0 , 625   .   22 , 4   =   14   l  

Vì oxi chiếm 1/5 V_kk => V_kk = 5.14 = 70 (lít)

\(m_{C_2H_4}=5.6\left(g\right)\)

\(n_{C_2H_4}=\dfrac{5.6}{28}=0.2\left(mol\right)\)

\(C_2H_4+Br_2\rightarrow C_2H_4Br_2\)

\(V_{CH_4}=11.2-0.2\cdot22.4=6.72\left(l\right)\)

\(n_{CH_4}=\dfrac{6.72}{22.4}=0.3\left(mol\right)\)

\(m_{CH_4}=0.3\cdot16=4.8\left(g\right)\)

\(CH_4+2O_2\underrightarrow{t^0}CO_2+2H_2O\)

\(C_2H_4+3O_2\underrightarrow{t^0}2CO_2+2H_2O\)

\(V_{O_2}=\left(0.3\cdot2+0.2\cdot3\right)\cdot22.4=26.88\left(l\right)\)

a. \(CH_4+2O_2\underrightarrow{t^o}CO_2+2H_2O\)

     a          2a      a

\(C_2H_4+3O_2\underrightarrow{t^o}2CO_2+2H_2O\)

  b          3b       2b

b. \(n_{O_2}=\dfrac{25.88}{22.4}=1.155mol\)

n hỗn hợp khí \(=\dfrac{11.2}{22.4}=0.5mol\)

Ta có: \(\left\{{}\begin{matrix}a+b=0.5\\2a+3b=1.155\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0.345\\b=0.155\end{matrix}\right.\)

\(\%V_{CH_4}=\dfrac{0.345\times22.4\times100}{11.2}=69\%\)

\(\%V_{C_2H_4}=100-69=31\%\)

c. \(V_{CO_2}=\left(a+2b\right)\times22.4=\left(0.345+2\times0.155\right)\times22.4=14.672l\)