Chemistry 9701 · AS & A Level · Chemical energetics

Chemical energetics — practice question

When magnesium carbonate is heated in a Bunsen burner flame, it decomposes. The values of the standard enthalpies of formation, $\Delta H_f^\circ$, for the species present are given below. $\Delta H_f^\circ\,\text{MgCO}_3 = -1095.8\,\text{kJ mol}^{-1}$ $\Delta H_f^\circ\,\text{MgO} = -601.7\,\text{kJ mol}^{-1}$ $\Delta H_f^\circ\,\text{CO}_2 = -393.5\,\text{kJ mol}^{-1}$ Calculate the standard enthalpy change for the decomposition of magnesium carbonate.

  • A$+100.6\,\text{kJ mol}^{-1}$
  • B$+887.6\,\text{kJ mol}^{-1}$
  • C$+1095.8\,\text{kJ mol}^{-1}$
  • D$+2091\,\text{kJ mol}^{-1}$

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