In what proportion of volume are mixed methane and air ($ 20\%$ in volume oxygen) to obtain the most explosive mixture?
$ 2C_2H_6 +7O_2 \; \rightarrow \; 4CO_2 + 6H_2O$
$ 2 \;mol $ ethane form the most explosive mixture with $ 7 \; mol\; O_2 $
Ideal Gas Law:
$ \frac{2RT}{P} \; L $ ethane form the most explosive mixture with $ \frac{7RT}{P} \; L \; O_2$, so with $ \frac {35RT}{P} \; L $ air
$\frac{V_{air}}{V_{ethane}}=\frac{\frac{35RT}{P}}{\frac{2RT}{P}}=\frac{35}{2}$
