I have this reaction, for which I need the standard enthalpy of reaction:

$$\ce{CuO (s) + H2S (g) \rightarrow CuS (s) + H2O (g)}$$

This is the data from the NIST web book (standard formation enthalpies, $\mathrm{kJ}\cdot\mathrm{mol}^{-1}$):

  • $\ce{CuO (s)}$: -156.60
  • $\ce{H2S (g)}$: -20.5
  • $\ce{H2O (g)}$ -241.83

There are no data tabulated for $\ce{CuS (s)}$, so how can I compute the standard reaction enthalpy lacking this data?

  • 1
    $\begingroup$ To put it bluntly, you can't. $\endgroup$ Jun 21, 2017 at 21:39

1 Answer 1


The standard enthalpy of formation of $\ce{CuS}\,\mathrm{(s)}$ is -48.4 $\mathrm{kJ}\cdot\mathrm{mol}^{-1}$. See this reference for your requested data and more.


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