Write a balanced chemical equation for the complete combustion of hexane (C6H14).
The correct answer and explanation is:
Balanced Chemical Equation:
2 C₆H₁₄ + 19 O₂ → 12 CO₂ + 14 H₂O
Explanation:
Complete combustion is a chemical reaction where a hydrocarbon reacts fully with oxygen to produce carbon dioxide and water. In the case of hexane (C₆H₁₄), it is a hydrocarbon composed of 6 carbon atoms and 14 hydrogen atoms. During complete combustion, each carbon atom forms carbon dioxide (CO₂), and each pair of hydrogen atoms forms one water molecule (H₂O).
To write a balanced combustion reaction for hexane:
- Start with the unbalanced formula:
C₆H₁₄ + O₂ → CO₂ + H₂O - Balance carbon atoms:
Hexane has 6 carbon atoms, so place a coefficient of 6 in front of CO₂:
C₆H₁₄ + O₂ → 6 CO₂ + H₂O - Balance hydrogen atoms:
Hexane has 14 hydrogen atoms. Each water molecule has 2 hydrogen atoms, so divide 14 by 2 to get 7:
C₆H₁₄ + O₂ → 6 CO₂ + 7 H₂O - Balance oxygen atoms:
There are now a total of (6 × 2) = 12 oxygen atoms in CO₂ and (7 × 1) = 7 oxygen atoms in H₂O. That adds up to 19 oxygen atoms. Since each O₂ molecule has 2 oxygen atoms, divide 19 by 2:
C₆H₁₄ + 19/2 O₂ → 6 CO₂ + 7 H₂O - Clear the fraction by multiplying the entire equation by 2:
2 C₆H₁₄ + 19 O₂ → 12 CO₂ + 14 H₂O
This final balanced equation shows that two molecules of hexane require nineteen molecules of oxygen to fully combust, producing twelve molecules of carbon dioxide and fourteen molecules of water. This process releases energy and is used in engines and heating systems.
