Chemistry 9701 · AS & A Level · Chemical energetics

Chemical energetics — practice question

Hydrogen sulfide, $\text{H}_2\text{S}$, is emitted by volcanoes. It then reacts with oxygen in the air to produce sulfur dioxide. $2\text{H}_2\text{S}(g) + 3\text{O}_2(g) \rightarrow 2\text{H}_2\text{O}(l) + 2\text{SO}_2(g)$ $\Delta H_f^\circ[\text{H}_2\text{S}(g)] = -21\ \text{kJ mol}^{-1}$ $\Delta H_f^\circ[\text{H}_2\text{O}(l)] = -286\ \text{kJ mol}^{-1}$ $\Delta H_f^\circ[\text{SO}_2(g)] = -297\ \text{kJ mol}^{-1}$ What is the standard enthalpy change for this reaction?

  • A$-1208\ \text{kJ mol}^{-1}$
  • B$-1124\ \text{kJ mol}^{-1}$
  • C$-562\ \text{kJ mol}^{-1}$
  • D$-541\ \text{kJ mol}^{-1}$

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