Answer:
A) 5.0 atm
Step-by-step explanation:
You want to know the pressure in a 1 L flask at 300 K when 0.03 mol of C₃H₈ reacts completely with O₂.
Reaction
We suppose the reaction of interest is ...
C₃H₈(g) +5O₂(g) ⇒ 3CO₂(g) +4H₂O(g)
This shows us there are 3+4 = 7 moles of products for each mole of C₃H₈ in the reaction. That is, there will be 0.03 mole × 7 = 0.21 mole of products.
Gas law
The gas law equation tells us the final pressure can be computed by ...
PV = nRT
P = nRT/V = (0.21 mol)(0.082 L·atm/(mol·K)(300 K)/(1 L) ≈ 5.166 atm
The total pressure in the flask after the reaction is closest to ...
A) 5.0 atm