Chemistry 9701 · AS & A Level · Chemical energetics

Chemical energetics — practice question

Enthalpy changes of combustion may be applied to work out enthalpy changes of formation. The equation below shows the enthalpy change of formation of butane. $4\text{C}(s) + 5\text{H}_2(g) \rightarrow \text{C}_4\text{H}_{10}(g)$ Using the standard enthalpy of combustion data given below, what is the numerical value of the standard enthalpy change of formation, $\Delta H_f^{\circ}$, for this reaction?

  • A$-5883\,\text{kJ mol}^{-1}$
  • B$-129\,\text{kJ mol}^{-1}$
  • C$+129\,\text{kJ mol}^{-1}$
  • D$+2197\,\text{kJ mol}^{-1}$

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