2 C₃H₆(g) + 9 O₂(g) → 6 CO₂(g) + 6 H₂O(g)

Understanding Entropy

Entropy (S) is a measure of disorder or randomness in a system. Here's how it applies to chemical reactions:

* Increased Disorder = Increased Entropy: Reactions that produce more molecules or molecules with greater freedom of movement (like gases) generally have a positive entropy change (ΔS > 0).

* Decreased Disorder = Decreased Entropy: Reactions that result in fewer molecules or more restricted movement (like solids) generally have a negative entropy change (ΔS < 0).

Analyzing the Reaction

* Reactants: We start with 2 moles of C₃H₆ and 9 moles of O₂, totaling 11 moles of gas.

* Products: We end with 6 moles of CO₂ and 6 moles of H₂O, totaling 12 moles of gas.

Key Observations:

* More Moles of Gas: The number of gas molecules increases from 11 to 12. This signifies increased disorder, leading to a positive entropy change.

* Similar Molecular Complexity: Both reactants and products contain relatively simple molecules. This factor doesn't contribute significantly to the entropy change.

Conclusion

The reaction 2 C₃H₆(g) + 9 O₂(g) → 6 CO₂(g) + 6 H₂O(g) has a positive entropy change (ΔS > 0). This is primarily due to the increase in the number of gas molecules.

Important Note: This analysis is based on general trends and does not provide a precise quantitative value for the entropy change. A more accurate determination would require using standard molar entropy values for each reactant and product.