Final answer:
The missing coefficient for CO₂ in the combustion reaction of hexane is 6, resulting in the balanced chemical equation: C₆H₁₂ + 9 O₂ → 6 CO₂ + 6 H₂O.
Step-by-step explanation:
To determine the missing coefficient for carbon dioxide (CO₂) in the combustion reaction of hexane (C₆H₁₂), we must ensure that the number of atoms of each element is the same on both sides of the equation. To begin balancing the equation, we can start with carbon atoms. Since there are 6 carbon atoms in hexane, we will need 6 molecules of CO₂ since each CO₂ has one carbon atom. Therefore, the balanced equation, including the unknown coefficient for carbon dioxide, is:
C₆H₁₂(l) + 9 O₂(g) → 6 CO₂(g) + 6 H₂O(g)
By doing so, we have 6 carbon atoms on both sides of the equation which satisfies the Law of Conservation of Mass.