Chemistry 0620 · IGCSE · Exothermic and endothermic reactions

Exothermic and endothermic reactions — practice question

The combustion equation for hydrazine, $\text{N}_2\text{H}_4$, is given here. $\text{N}_2\text{H}_4 + \text{O}_2 \rightarrow \text{N}_2 + 2\text{H}_2\text{O}$. The bond energies are: $\text{N-H}=391\ \text{kJ mol}^{-1}$, $\text{N=N}=409\ \text{kJ mol}^{-1}$, $\text{N}\equiv\text{N}=944\ \text{kJ mol}^{-1}$, $\text{O-H}=463\ \text{kJ mol}^{-1}$, $\text{O=O}=496\ \text{kJ mol}^{-1}$. What is the total enthalpy change for the combustion of one mole of hydrazine?

  • A$-327\ \text{kJ mol}^{-1}$
  • B$-111\ \text{kJ mol}^{-1}$
  • C$+111\ \text{kJ mol}^{-1}$
  • D$+327\ \text{kJ mol}^{-1}$

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