Ammonia gas and hydrochloric acid vapor undergo a reaction to produce solid ammonium chloride. The reaction equation is given below together with relevant thermodynamic data at 298K:
NH3 (g) + HCl(g) --> NH4Cl(s)
ΔHf -46.11 -92.31 -314.4 kJ/mol
ΔS 192.3 186.8 94.56 J/molK
Calculate the standard enthalpy change, ΔHr and the standard entropy change ΔSr for the reaction as written. Show details of your calculation. Now calculate the total entropy change ΔStot for the system plus it surroundings, and verify that the reaction is spontaneous at 298K. Confirm your conclusion by calculating ΔGr, the Gibbs free energy change for the reaction. Based on the signs of ΔHr and ΔSr state whether or not the reaction is favorable at all temperatures. If the reaction is favorable only over a limited temperature range, calculate the temperature at which the change in behavior occurs.