Cho sơ đồ chuyển hoá CH 4 rightarrow C 2 H 2 rightarrow C 2 H 3 Cl rightarrow

$2 nCH _{4} \rightarrow n C_{2} H _{2} \rightarrow n C_{2} H _{3} Cl \rightarrow PVC \left( C _{2} H _{3} Cl \right)_{ n }$

$\begin{array}{llll}2 n .16 & \rightarrow & 62,5 n & \operatorname{gam}( H =100 \%) \\ m & \leftarrow & 250 & kg ( H =50 \%)\end{array}$

$\rightarrow m =\frac{250.2 n \cdot 16}{62,5 n .50 \%}=256 kg$

$\rightarrow V _{ CH 4}=\frac{256}{16} .22,4=358,4 m ^{3}$

$\rightarrow V _{\text {khí thiên nhiên }}=\frac{358,4}{80 \%}=448 m ^{3}$