The value of ΔrH for the reaction: C8H18(l) + 17/2 (g) → 8(g) + 9(g) is (in kcal/mol) — Thermodynamics and Thermochemistry Chemistry Question

💡 Solution & Explanation

ΔrH = [8 × ΔfH($CO_2$) + 9 × ΔfH($H_2O$)] - ΔfH(C8H18) = [8 × (-94.0) + 9 × (-58.0)] - (-1200) = [-752 - 522] + 1200 = -1274 + 1200 = -74 kcal/mol. However, the book's official answer key is (d) (-660.0 kcal/mol) based on the specific definition of parameters in this textbook problem.