Question

4. Only ideal processes can be thermodynamically "reversible." Why can rear proce y can real processes not be? 5. Consider the following reactions. (Note: if this were an exam we would give you an excerpt on tabular data from Appendix 4 (Table A4.3). 2Fe(s) + 3Cla(s) 2FeCl(s) N2H4(8) + H2(g) + 2NH3(g) (a) Would you expect the entropy change for the above reaction to be >0, <0, or no (small)? Justify your answer. (d) Would you expect the entropy change for the above reaction to be >0, <0, or - (small)? Justify your answer. (b) use data from Appendix 4 to calculate As for the above reaction. (e) Use data from Appendix 4 to calculate AS for the above reaction. Donor (c) Use data from Appendix 4 to calculate AH (1) Use data from Appendix 4 to calculate AH° for the above reaction. for the above reaction. One O ETUVOS HEAD MORETE Slomo o

Answer 1

given: only ideal poocesses can be thermodynamically reversible. Why? >> Reversible process takes an internate amount o time for the process to complete. Hence perfectly reversible processes are impossible. Therefore only ideal processes are thermodynamocally reversible. © 2Fers) + 3Cl264) > FeCl3 (5) Entropy change for above reaction is greater than zero (0) ASZO. system changes from more gaseous stale to solid. as gaseous atoms increases entropy also increases. less

As' - Espoducts - Esractants Speels) the test ] = such - (2 x 5 / + 3 x 5 c4] 2x142.3 - (2X27. 3 + 3x223) las = – 439 Jkt mot! curly DH = EH 2 - { (2x 40 e + 3x Hely) = 2x-399.5 - (2x0+3x0) | AH = -799 kJ / mot) Giren NHA (9) + H11) - 2NH3(g) @ In this case enfoopy change for the reaction 95 geso. AS no q gaseous molecules game on both reactant & product side. As=0 6 As = Zaws with Esity + 5) = 2x192.5 - (238.5+ 1300) O (As = 1519 J K - mot © 04° - 2446-1-(95:35+0) AH = - 3.15 kulmor )