Answer:
13
Explanation:
Let's consider the unbalanced equation for the combustion of propane.
C₃H₈ + O₂ ⇒ CO₂ + H₂O
We will begin balancing H atoms by multiplying H₂O by 4.
C₃H₈ + O₂ ⇒ CO₂ + 4 H₂O
Now, we balance C atoms by multiplying CO₂ by 3.
C₃H₈ + O₂ ⇒ 3 CO₂ + 4 H₂O
Finally, we get the balanced equation multiplying O₂ by 5.
C₃H₈ + 5 O₂ ⇒ 3 CO₂ + 4 H₂O
The sum of the coefficients is 1 + 5 + 3 + 4 = 13.
