Chemistry 9701 · AS & A Level · Chemical energetics

Chemical energetics — practice question

An enthalpy change equation is presented below. The enthalpy change is $Q$. $2\text{C}(s) + 3\text{H}_2(g) + 3.5\text{O}_2(g) \xrightarrow{Q} 2\text{CO}_2(g) + 3\text{H}_2\text{O}(l)$ What expression should be used to calculate $Q$?

  • A$2 \times \Delta H_f^\circ[\text{CO}_2(g)] - 3 \times \Delta H_f^\circ[\text{H}_2(g)]$
  • B$3 \times \Delta H_f^\circ[\text{H}_2\text{O}(g)] + 2 \times \Delta H_c^\circ[\text{CO}_2(g)]$
  • C$2 \times \Delta H_f^\circ[\text{CO}_2(g)] - 3 \times \Delta H_f^\circ[\text{H}_2(g)]$
  • D$3 \times \Delta H_f^\circ[\text{H}_2\text{O}(l)] + 2 \times \Delta H_f^\circ[\text{CO}_2(g)]$

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