Liquid octane reacts with oxygen gas to form carbon dioxide gas and water vapor. what is the balanced chemical equation?
The Correct Answer and Explanation is:
Here is the balanced chemical equation for the combustion of liquid octane:
C₈H₁₈(l) + 12.5 O₂(g) → 8 CO₂(g) + 9 H₂O(g)
Since chemical equations typically avoid fractional coefficients, multiplying the entire equation by 2 gives:
2 C₈H₁₈(l) + 25 O₂(g) → 16 CO₂(g) + 18 H₂O(g)
Explanation:
Combustion reactions involve the reaction of a hydrocarbon with oxygen gas, resulting in the production of carbon dioxide and water vapor. Octane (C₈H₁₈) is a hydrocarbon commonly found in gasoline. During its combustion, each carbon atom in octane forms one molecule of carbon dioxide, while the hydrogen atoms combine with oxygen to form water vapor.
The balancing process begins with the hydrocarbon. Octane contains 8 carbon atoms and 18 hydrogen atoms. Therefore, the products must contain 8 carbon dioxide molecules (since each CO₂ has one carbon) and 9 water molecules (since each H₂O has two hydrogen atoms, and 18 hydrogen atoms divided by 2 equals 9 water molecules).
Next, the oxygen atoms are balanced. From the products, 8 CO₂ molecules contribute 16 oxygen atoms, and 9 H₂O molecules contribute 9 oxygen atoms, giving a total of 25 oxygen atoms on the product side. Because oxygen gas (O₂) contains two oxygen atoms per molecule, dividing 25 by 2 gives 12.5 O₂ molecules.
To eliminate the fractional coefficient, all coefficients are multiplied by 2, resulting in whole numbers: 2 molecules of octane react with 25 molecules of oxygen gas to produce 16 molecules of carbon dioxide and 18 molecules of water vapor. This fully balanced equation satisfies the law of conservation of mass, ensuring that the number of each type of atom is equal on both sides of the equation.
