10 moles of ethane is supplied with 49 moles of oxygen, what

10-moles-of-ethane-is-supplied-with-49-moles-of-oxygen-what

10 moles of ethane is supplied with 49 moles of oxygen, what is the percentage of excess oxygen?
A. 20%
B. 40%
C. 50%
D. 70%
Correct option is B. 40%

The balanced reaction is C2H6 + 3.5O2 -> 2CO2 + 3H2O, => O2 required = 3.5*10 = 35 moles, => percentage of excess oxygen = 100*(49 – 35)/35 = 40%.