Chemistry 9701 · AS & A Level · Chemical energetics

Chemical energetics — practice question

For this question, the following data will be required. $\Delta H_f^\circ(\text{N}_2\text{H}_4(l)) = 50.6\,\text{kJ mol}^{-1}$ $\Delta H_f^\circ(\text{N}_2\text{O}_4(g)) = 9.2\,\text{kJ mol}^{-1}$ $\Delta H_f^\circ(\text{H}_2\text{O}(g)) = -241.8\,\text{kJ mol}^{-1}$ Hydrazine, $\text{N}_2\text{H}_4(l)$, reacts with dinitrogen tetraoxide, $\text{N}_2\text{O}_4(g)$, to produce nitrogen gas and water vapour. $2\text{N}_2\text{H}_4(l) + \text{N}_2\text{O}_4(g) \rightarrow 3\text{N}_2(g) + 4\text{H}_2\text{O}(g)$ What is the enthalpy change for this reaction?

  • A$-1077.6\,\text{kJ mol}^{-1}$
  • B$-856.8\,\text{kJ mol}^{-1}$
  • C$-301.6\,\text{kJ mol}^{-1}$
  • D$-182.0\,\text{kJ mol}^{-1}$

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