If 4.20 mol of ethane, C2H6, undergo combustion according to the unbalanced equation given below, how many moles of oxygen are required?

The Balance Chemical equation for said reaction is as follow,

C₂H₆ + 3.5 O₂ → 2 CO₂ + 3 H₂O

Or,

2 C₂H₆ + 7 O₂ → 4 CO₂ + 6 H₂O

According to equation,

2 moles of Ethane react completely with = 7 moles of Oxygen

So,

4.20 moles of Ethane will react with = X moles of Oxygen

Solving for X,

X = (4.20 mol * 7 mol) : 2 mol

X = 14.7 moles of Oxygen

Result:

14.7 moles of Oxygen are required to react with 4.20 moles of Ethane for complete reaction.