C3H8 + 5O2 ===> 3CO2 + 4H2O (our balanced reaction)
Data:
3.58 moles of O2
The text already gives us the excess limiting, C3H8, so O2 is the limiting reactant.
Procedure:
5 moles O2 -------- 4 moles H2O
3.58 moles O2 -------- X
X = 2.86 moles of H2O
Answer: 2.86 moles H2O