Using the bond energies (kJ/mol) N≡N 945, H–H 436, N–H 391, estimate the enthalpy change for N + 3H → 2NH.
Answer and explanation
Correct answer: A. -93 kJ
- Step 1: .
- Step 2: Substituting the bond energies gives kJ.
Answer
-93 kJ.
Why not the others: +93 kJ: the sign is reversed, which would make the reaction endothermic.
Practise more Thermochemistry.
Free questions with an explanation for every one, and full timed EJU Japan mock tests.
More Thermochemistry questions
- Using the bond energies (kJ/mol) H–H 436, Cl–Cl 243, H–Cl 432, estimate the enthalpy change for H + Cl → 2HCl.
- Using the bond energies (kJ/mol) H–H 436, F–F 155, H–F 565, estimate the enthalpy change for H + F → 2HF.
- Using the bond energies (kJ/mol) H–H 436, Br–Br 193, H–Br 366, estimate the enthalpy change for H + Br → 2HBr.