Chemistry 9701 · AS & A Level · Chemical energetics

Chemical energetics — practice question

Calcium carbide, $\text{CaC}_2$, reacts with water, as illustrated. The information below the equation gives, in $\text{kJ mol}^{-1}$, the standard enthalpies of formation for the compounds taking part. $\text{CaC}_2(s) + \text{H}_2\text{O}(l) \rightarrow \text{CaO}(s) + \text{C}_2\text{H}_2(g)$ What is the standard enthalpy change for the reaction shown?

  • A$-753\ \text{kJ mol}^{-1}$
  • B$-61\ \text{kJ mol}^{-1}$
  • C$+61\ \text{kJ mol}^{-1}$
  • D$+753\ \text{kJ mol}^{-1}$

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