Using bond energies H–H = 436, Cl–Cl = 243 and H–Cl = 432 kJ mol⁻¹, what is ΔH for H₂(g) + Cl₂(g) → 2HCl(g)?
Correct answer C. −185 kJ mol⁻¹
Explanation
ΔH = bonds broken − bonds formed = (436 + 243) − (2 × 432) = 679 − 864 = −185 kJ mol⁻¹. Forgetting the factor of 2 gives +247.
Answer checked How we write and check questions
Discussion