How many liters of oxygen is required for complete combustion of 6 gms of ethane at S.T.P.

${\mathrm{C}}_2{\mathrm{H}}_6+\frac{7}{2}{\mathrm{O}}_2\to 2{\mathrm{CO}}_2+3{\mathrm{H}}_2\mathrm{O}$

1 mole of ${\mathrm{C}}_2{\mathrm{H}}_6$ . . . . . . .$\frac{7}{2}\mathrm{moles}\mathrm{of}{\mathrm{O}}_2$

30 grs    ----------------------- $\frac{7}{2}\times 22.4 \mathrm{lit}$

6 grs  -------------------------  ?

$6\times \frac{7}{2}\times \frac{22.4}{30}$

$=15.68 \mathrm{lit}$