CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics
Problem
From a comparative bar chart, a student extracts the average bond energies (in kJ·mol⁻¹) listed below and wishes to estimate ΔH for the combustion of acetylene:
C≡C 839 C–H 413 O=O 498 C=O ( CO₂ ) 799 O–H 463
Reaction (as written):
2 C₂H₂(g) + 5 O₂(g) → 4 CO₂(g) + 2 H₂O(g)
Using only the data provided, what is the approximate enthalpy change for the reaction?
(a) −1.50 × 10³ kJ·mol⁻¹
(b) +2.42 × 10³ kJ·mol⁻¹
(c) −2.42 × 10³ kJ·mol⁻¹
(d) −4.85 × 10³ kJ·mol⁻¹