# Where can I find the standard molar entropy for ammonium bicarbonate?

I'd like to know the standard molar entropy S0solid for ammonium bicarbonate to use in an example in class, to calculate ΔS0 for the reaction, NH4HCO3(s) → NH3(g) + H2O(g) + CO2(g).

Already checked: Wikipedia, NIST Chemistry WebBook, Google. I don't have access to the CRC handbook.

(Arthur and Chester Miller already found the standard enthalpy of formation for ammonium bicarbonate, in this forum, in 2016; and it's in the German Wikipedia.)

## 1 Answer

“Standard Thermodynamic Properties of Chemical Substances”, in CRC Handbook of Chemistry and Physics, 90th Edition (CD-ROM Version 2010), David R. Lide, ed., CRC Press/Taylor and Francis, Boca Raton, FL. gives values for the standard molar enthalpy of formation $\Delta_\mathrm fH^\circ$, the standard molar Gibbs energy of formation $\Delta_\mathrm fG^\circ$, and the standard molar entropy $S^\circ$ (all at $T=298.15\ \mathrm K$ and $p=100\ \mathrm{kPa}=1\ \mathrm{bar}$) of crystalline ammonium hydrogen carbonate as follows. \begin{align} \Delta_\mathrm fH^\circ&=-849.4\ \mathrm{kJ/mol}\\ \Delta_\mathrm fG^\circ&=-665.9\ \mathrm{kJ/mol}\\ S^\circ&=120.9\ \mathrm{J/(mol\ K)} \end{align}