Assume all gases are perfect unless stated otherwise. Note that 1 atm = 1.013 25 bar. Unless otherwise stated, thermochemical data are for 298.15 K. The standard enthalpy of formation of the metallocene bis(benzene)chromium was measured in a calorimeter. It was found for the reaction $\mathrm{Cr}\left(\mathrm{C}_6 \mathrm{H}_6\right)_2(\mathrm{~s}) \rightarrow \mathrm{Cr}(\mathrm{s})+2 \mathrm{C}_6 \mathrm{H}_6(\mathrm{~g})$ that $\Delta_{\mathrm{r}} U^{\bullet}(583 \mathrm{~K})=+8.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$. Estimate the standard enthalpy of formation of the compound at $583 \mathrm{~K}$. The constant-pressure molar heat capacity of benzene is $136.1 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$ in its liquid range and $81.67 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$ as a gas.
+116.0