Combustion of Alkanes: What's the Deal?

📌 CONCEPT: The combustion of alkanes is a chemical reaction that produces carbon dioxide and water vapor, with the ratio of CO2 to H2O depending on the alkane's molecular structure.

📐 RULE / FORMULA: According to the balanced chemical equation for the combustion of n-butane (C4H10), 2 moles of n-butane produce 4 moles of CO2 and 5 moles of H2O.

💡 WORKED EXAMPLE: Let's consider the combustion of n-butane (C4H10): 2C4H10 + 13O2 → 8CO2 + 10H2O. From this equation, we see that for every 2 moles of n-butane, 4 moles of CO2 are produced. Similarly, 5 moles of H2O are produced. This ratio is not the same for methane (CH4) because its combustion produces only 2 moles of CO2 and 2 moles of H2O for every 1 mole of CH4.

⚠️ COMMON MISTAKE: Students often confuse the ratio of CO2 to H2O produced during the combustion of different alkanes, thinking that the ratio remains constant for all alkanes. However, the ratio depends on the alkane's molecular structure and the balanced chemical equation for its combustion.