Chemistry 9701 · AS & A Level · Chemical energetics

Chemical energetics — practice question

When sodium burns in oxygen, heat energy is released and the compound $\text{Na}_2\text{O}$ is produced. The reaction equation is shown below. $2\text{Na}(s) + \frac{1}{2}\text{O}_2(g) \rightarrow \text{Na}_2\text{O}(s)$ Which statement about this reaction is correct?

  • A$\Delta H^\circ$ for the reaction is equal to twice the bond energy of the Na-O bond.
  • B$\Delta H^\circ$ for the reaction is positive.
  • CThe equation represents the standard enthalpy change of combustion of sodium.
  • DThe equation represents the standard enthalpy change of formation of sodium oxide.

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