Question

8. For the following reaction, CC2(s) + 2H2O(l) + Ca(OH)2(s) + C2H2(g) which is spontaneous at all temperatures, one would predict that a. AG is positive for all temperatures. d. AH is - and AS is for the reaction. b. AH is + and AS is for the reaction. e. AH is + and AS' is- for the reaction. c. AH is - and AS is for the reaction. 9. Calculate the standard absolute entropy, in J/mol K. of Mg: AS = -462.1 J/K S®(Mg(NO)2) = 39.2 J/mol K 2NO(g) + 2MgO(s) → Mg(NO),(s) + Mg(s) S®(NO) = 239.9 J/mol K S®(MgO) = 27.0J/mol K a. 325 1.234.3 c. 278 10. If a reaction is exothermic and nonspontaneous at 25 C then it a. can never be spontaneous. b. can become spontaneous by adding a catalyst. c. may be spontaneous at higher temperature. d. may be spontaneous at lower temperature 11. The heat of fusion of acetic acid is 11.5 kJ/mol. Its melting point is 16.6 'C. The change in entropy for the melting of acetic acid in J/mol Kis d. 39.7 c. 15.1 e.-115 a. 694 b. 11.5 12. At the boiling point of carbon disulfide, CS2, AH yap = 26.9 kJ/mol and AS vap = 84.5 J/mol K. Determine the normal boiling point temperature in 'C for CS2. a. -142 b. 0.32 c. 45 d. 130 e. 318 13. Consider the following equation carefully and determine the sign of AS' for the reaction it describes. NH4Br(s) → NH3(g) + HBr(g) AH® rxn = + 45.01 kcal Which of the following statements describes the thermodynamic spontaneity of the reaction? a. The reaction is spontaneous at all temperatures. b. The reaction is spontaneous only at relatively high temperatures. c. The reaction is spontaneous only at relatively low temperatures. d. The reaction is not spontaneous at any temperature. e. We cannot tell from the information given.

Answer 1

ansurr AS 39.2 -462. 2X 239.9 Mg 2x27) 462. 3-2 t S32.8 ng 3 2 S qndcue 3 2.S amu a-o 37 KK 11-5 AlH 11 T 16.6+273 31-1J/K 39. 7 31FK 26. AtH T E ES.5x 10 AS 45c amwEY 13 amu