Chemistry 0620 · IGCSE · Exothermic and endothermic reactions

Exothermic and endothermic reactions — practice question

The balanced equation for the complete combustion of ethyne, $\text{H-C} \equiv \text{C-H}$, is given below. $2\text{H-C} \equiv \text{C-H} + 5\text{O}=\text{O} \rightarrow 4\text{O}=\text{C}=\text{O} + 2\text{H-O-H}$ A list of bond energies is provided. What is the enthalpy change for the reaction when $1\,\text{mol}$ of ethyne is completely burned?

  • A$-2472\,\text{kJ mol}^{-1}$
  • B$-1236\,\text{kJ mol}^{-1}$
  • C$+1236\,\text{kJ mol}^{-1}$
  • D$+2472\,\text{kJ mol}^{-1}$

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