Chapter 14, Problem 14.46P

A good source for formation data for compounds is the NIST Chemistry WebBook site. Values of $\Delta H_f^{°}$ , but not of $\Delta G_f^{°}$ , are reported. Instead, values of absolute standard entropies S° are listed for compounds and elements. To illustrate the use of NIST data, let H₂O₂ be the compound of interest. Values provided by the Chemistry WebBook are as follows:

• 
• $S^{°}\left[H_2{O}_2\left(g\right)\right]=232.95J\cdot mo{l}^{-1}\cdot K^{-1}$
• $\begin{array}{l}\\ S^{°}\left[H_2\left(g\right)\right]=130.680J\cdot mo{l}^{-1}\cdot K^{-1}\end{array}$
• $\begin{array}{l}\\ S^{°}\left[O_2\left(g\right)\right]=205.152J\cdot mo{l}^{-1}\cdot K^{-1}\end{array}$

All data are for the ideal-gas state at 298.15 K and 1 bar. Determine a value of $\Delta G_{f_{298}}^{°}$ for H₂O₂(g).