Question

In the following reaction, how many liters of oxygen will react with 124.5 liters of propane (C3H8), at STP?
C3H8 + 5O2 d 3CO2 + 4H2O
A) 24.9 liters
B) 622.5 liters
C) 373.5 liters
D) 41.5 liters

Answer 1

According to stoichiometry, 1 litre of propane reacts with = 5 litres of O2. Therefore, 124.5 litres of propane will reacts with = 124.5 x 5 = 622.5 Litres of O2. Option B is correct.

Answer 2

The balanced chemical reaction would be;

C3H8 + 5O2 -----> 3CO2 + 4H2O 

We are given the volume of propane to be used in the reaction. We use this amount to calculate the oxygen needed. We do as follows:

124.5 L C3H8 ( 1 mol / 22.4 L C3H8 ) ( 5 mol O2 / 1 mol C3H8 ) ( 22.4 L / 1 mol ) = 622.5 L O2 needed