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

\(2C_2H_2+5O_2\underrightarrow{t^o}4CO_2+2H_2O\)

Ta có: \(n_{CH_4}+n_{C_2H_2}=\dfrac{6,72}{22,4}=0,3\left(mol\right)\left(1\right)\)

\(n_{CO_2}=n_{CH_4}+2n_{C_2H_2}=\dfrac{7,84}{22,4}=0,35\left(mol\right)\left(2\right)\)

Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}n_{CH_4}=0,25\left(mol\right)\\n_{C_2H_2}=0,05\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}\%V_{CH_4}=\dfrac{0,25.22,4}{6,72}.100\%\approx83,33\%\\\%V_{C_2H_2}\approx16,67\%\end{matrix}\right.\)

Theo PT: \(n_{O_2}=2n_{CH_4}+\dfrac{5}{2}n_{C_2H_2}=0,625\left(mol\right)\Rightarrow m_{O_2}=0,625.32=20\left(g\right)\)

\(a,Gọi\left\{{}\begin{matrix}n_{CH_4}=a\left(mol\right)\\n_{C_2H_4}=b\left(mol\right)\\n_{C_2H_2}=c\left(mol\right)\end{matrix}\right.\\ n_{hhkhí}=0,4\left(mol\right)\\ n_{CO_2}=\dfrac{15,68}{22,4}=0,7\left(mol\right)\\ n_{Br_2}=\dfrac{64}{160}=0,4\left(mol\right)\\ PTHH:C_2H_4+Br_2\rightarrow C_2H_4Br_2\\ Mol:a\rightarrow a\\ C_2H_2+2Br_2\rightarrow C_2H_2Br_4\\ Mol:b\rightarrow2b\\ CH_4+2O_2\underrightarrow{t^o}CO_2+2H_2O\\ Mol:a\rightarrow2a\rightarrow a\)

\(C_2H_4+3O_2\underrightarrow{t^o}2CO_2+2H_2O\\ Mol:b\rightarrow3b\rightarrow2b\\ 2C_2H_2+5O_2\underrightarrow{t^o}4CO_2+2H_2O\\ Mol:c\rightarrow2,5c\rightarrow2c\\ Hệ.pt\left\{{}\begin{matrix}a+b+c=0,4\\b+2c=0,4\\a+2b+2c=0,7\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,1\left(mol\right)\\b=0,2\left(mol\right)\\c=0,1\left(mol\right)\end{matrix}\right.\)

\(\%V_{CH_4}=\%V_{C_2H_2}=\dfrac{0,1}{0,4}=25\%\\ \%V_{C_2H_4}=\dfrac{0,2}{0,4}=50\%\)

\(m_{CH_4}=0,1.16=1,6\left(g\right)\\ m_{C_2H_4}=28.0,2=5,6\left(g\right)\\ m_{C_2H_2}=0,1.26=2,6\left(g\right)\\ \%m_{CH_4}=\dfrac{1,6}{1,6+5,6+2,6}=16,32\%\\ \%m_{C_2H_4}=\dfrac{5,6}{1,6+5,6+2,6}=57,14\%\\ \%m_{C_2H_2}=100\%-16,32\%-57,14\%=26,54\%\)

\(b,PTHH:C_2H_5OH\rightarrow C_2H_4+H_2O\\ Mol:0,2\leftarrow0,2\\ m_{C_2H_5OH}=0,2.46=9,2\left(g\right)\)

Dài quá!!!

Bài 1:

Ta có: \(n_{C_2H_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\)

PT: \(2C_2H_2+5O_2\underrightarrow{t^O}4CO_2+2H_2O\)

a, \(n_{O_2}=\dfrac{5}{2}n_{C_2H_2}=0,625\left(mol\right)\Rightarrow m_{O_2}=0,625.32=20\left(g\right)\)

b, \(n_{CO_2}=2n_{C_2H_2}=0,5\left(mol\right)\Rightarrow m_{CO_2}=0,5.44=22\left(g\right)\)

Bài 2:

Ta có: \(\%V_{C_2H_2}=\%V_{CH_4}=50\%\) (do tỉ lệ số mol 2 khí bằng nhau)

\(n_{hh}=\dfrac{3,36}{22,4}=0,15mol\)

\(n_{CO_2}=\dfrac{4,48}{22,4}=0,2mol\)

\(\left\{{}\begin{matrix}n_{CH_4}=x\left(mol\right)\\n_{C_2H_2}=y\left(mol\right)\end{matrix}\right.\)

\(CH_4+2O_2\rightarrow CO_2+2H_2O\)

\(C_2H_2+\dfrac{5}{2}O_2\rightarrow2CO_2+H_2O\)

Từ hai pt trên:\(\Rightarrow\left\{{}\begin{matrix}x+y=0,15\\x+2y=0,2\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=0,1\\y=0,05\end{matrix}\right.\)

\(\%V_{CH_4}=\dfrac{0,1}{0,1+0,05}\cdot100\%=66,67\%\)

\(\%V_{C_2H_2}=100\%-66,67\%=33,33\%\)

\(n_{CO_2}=\dfrac{V_{CO_2}}{22,4}=\dfrac{4,48}{22,4}=0,2mol\)

Gọi \(n_{CH_4}\) là x \(\Rightarrow V_{CH_4}=22,4x\)

      \(n_{C_2H_2}\) là y \(\Rightarrow V_{C_2H_2}=22,4y\)

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

  x                              x             ( mol )

\(2C_2H_2+5O_2\rightarrow\left(t^o\right)4CO_2+2H_2O\)

    y                              2y                    ( mol )

Ta có:

\(\left\{{}\begin{matrix}22,4x+22,4y=3,36\\x+2y=0,2\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=0,1\\y=0,05\end{matrix}\right.\)

\(\Rightarrow V_{CH_4}=22,4.0,1=2,24l\)

\(\Rightarrow V_{C_2H_2}=22,4.0,05=1,12l\)

\(\%V_{CH_4}=\dfrac{2,24}{3,36}.100=66,67\%\)

\(\%V_{C_2H_2}=100\%-66,67\%=33,33\%\)

nhh khí = 3,36/22,4 = 0,15 (mol)

Gọi nCH4 = a (mol); nC2H2 = b (mol)

a + b = 0,15 (1)

nCO2 = 4,48/22,4 = 0,2 (mol)

PTHH:

CH4 + 2O2 -> (t°) CO2 + 2H2O

a ---> 2a ---> a ---> 2a

2C2H2 + 5O2 -> (t°) 4CO2 + 2H2O

b ---> 2,5b ---> 2b ---> b

a + 2b = 0,4 (2)

(1)(2) => a = 0,1 (mol); b = 0,05 (mol)

%VCH4 = 0,1/0,15 = 66,66%

%C2H2 = 100% - 66,66% = 33,34%

Chọn B

Đáp án B

Chọn đáp án B

Để ý thấy các chất trong X là

đều có 4 nguyên tử C