Question

nupiel 17 Problems 1. Answer the following questions in terms of thermodynamic principles. a. Consider the reaction represented below, which is spontaneous at 298 K. CO2(g) + 2 NH3(g) -> CO(NH2)2(s) + H2O(l); AH = -134 kJ i. For the reaction, indicate whether the standard entropy change, AS, is positive, or negative, or zero. Justify your answer. ii. Which factor, the change in enthalpy, AH, or the change in entropy, AS, provides the principal driving force for the reaction at 298 K? Explain. iii. For the reaction, how is the value of the standard free energy change, AGº, affected by an increase in temperature? Explain. b. Some reactions that are predicted by their sign of 4Gº to be spontaneous at room temperature do not proceed at a measurable rate at room temperature. i. Account for this apparent contradiction. ii. A suitable catalyst increases the rate of such a reaction. What effect does the catalyst have on AG°for the reaction? Explain.

Answer 1

2NH3 L9) CO(NH2)2 15) + Holl) 19) CO2 (g) + and all are gaseous. Reutant side. Toral moles = 3 and solid & liquid Product side : Two mores more no. of moles since Reactant side has gaseous. and all reagents are > Product pro Reactant so entropy IS) (i) then as = s product - Sreactant Ascol Li Duo - DHTOS or as will change on change in DH for so ou provides de primerple driving force reaction at 248 k upon DH or Aso. the ( since Do - DH - TDS Hº and Ds both are Negative It means - TAS DO Now TT = TDS T so if ToS = DH [Dh'=ol TASS DH = 100 so]