3. Calculate S at 25°C for the reduction of a given these absolute entropies: 2PBO(s) + C(s) 2Pb(s) + CO2(g) Given: S° (J/K.mol) 69.54 5.7 64.89 213.6

7. The decomposition of ammonium chloride to form ammonia and hydrogen chloride occurs NH,Cl→ NH3(e + HCle AH = 176 kJ according to the following reaction: a) Predict the sign of the entropy change, AS, for this reaction. Justify your answer. b) The value of AG° for the reaction is negative at high temperatures but positive at low temperatures. Explain.

W ↑ To determine the spontaneity of a chemical reaction, the sign of AG rather than the sign of AS is generally used. This is because O (1) AG is always positive and AS may be positive or negative O (2) Free energy free and it is easier to understand than entropy. O (3) AG is always larger than AS O (4) none given #3 3 A Moving to the next question prevents changes to this answer. E C $ 4 D R G Search or type URL % 5 MacBook Pro T (O G Y & 7 H U * 8 J 9 K 0 1 L Questi P

Calculate ΔS° (J/mol-K) for the reaction below, given the thermodynamic data in the table.  1 A(s) + 4 B(g) → 1 C(s) + 3 D(g) Substance S°(J/mol-K) A(s) 196.9 B(g) 81.80 C(s) 131.1 D(g) 59.30

Entropy Changes (AS rxn) ; Read Section 19.7. You can click on the Review link to access the section in your e Text. Substance S° (J/(mol. K)) 5.7 2.4 C(s, graphite) C(s, diamond) H(g) H₂(g) Cl(g) Cl₂ (g) CH3 Cl(g) 114.7 130.7 165.2 223.1 234.6 Find AS for the formation of CH3C1(g) from its elements in their standard states. Express your answer in joules per kelvin to one decimal place. ΠΟΠΗ ΑΣΦ ASixn= - Submit Previous Answers Request Answer X Incorrect; Try Again; 5 attempts remaining 1 ? J/K

1. For which of the following processes would ΔS° be expected to be most positive? Group of answer choices A. H2O(l) → H2O(s) B. 2NO2(g) → N2O4(g) C. NH3(g) + HCl(g) → NH4Cl(s) D.O2(g) + 2H2(g) → 2H2O(g) E. 2N2H4(g) → 2NH3(g) + N2(g) + H2(g) F. O2(g) + 2H2(g) → 2H2O(g)   2. For the process HX(s) → HX(l), ΔH° = 9.17 kJ/mol and ΔS° = 43.9 J/mol/K. What is the melting point of HX? ΔΔ G = ΔΔ H - T ΔΔ S Group of answer choices A. –130 °C B. 130 °C C. 209 °C D. 64 °C E. –64 °C   3. Substance X has a heat of vaporization of 45.1 kJ/mol at its normal boiling point (423°C). For the process X(l) → X(g) at 1 atm and 423°C calculate the value of ΔSsurr. ΔΔSsurroundings = -ΔΔHsystem/T Group of answer choices A. –64.8 J/K mol B. –107 J/K mol C. 0 D. 107 J/K mol E. 64.8 J/K mol

19 Thermodynamic Quantities for Selected Substances at 298.15 K (25°C) AHf AGf AS° AHf (kJ/mol) AGf (kJ/mol) AS° Substance (kJ/mol) (kJ/mol) (J/mol-K) Substance (J/mol-K) Aluminum Chlorine CI (g) C (аq) Cl2 (g) HCI (aq) HCI (g) Chromium Al (s) AIC13 (s) 28.32 121.7 105,7 - 131,2 165.2 - 705.6 - 630.0 109.3 - 167.2 56.5 Al203 (s) - 1669.8 1576.5 51.00 222,96 - 131.2 -95.27 - 167.2 56.5 186,69 Barium - - Ba(s) BaCO3(s) BaO(s) Beryllium Be(s) 63.2 -92.30 - 1216,3 - 553.5 - 1137.6 112.1 Cr (g) Cr (s) Cr203 (s) Cobalt Со (g) Copper Cu (s) CuCl2 (s) CuO (s) - 525.1 70.42 397.5 352.6 174.2 23.6 9.44 - 1139.7 - 1058.1 81.2 BeO(s) Be(ОН)2(8) 13.77 50.21 - 608.4 -579,1 - 817.9 - 905.8 439 393 179 Bromine 111.8 - 120.9 Br(g) Br-(aq) Br2(g) Br2(1) HBr(g) Calcium Ca(g) Ca(s) CaCO3 (s, calcite) CaCl2(s) CaF2(s) CaO(s) Ca(OH)2(s) CaSO4(s) 82.38 174.9 33.30 108.1 - 102.8 - 167,7 - 128,3 - 147.9 80.71 - 205.9 30,71 3.14 245.3 - 156,1 42,59 - Cu20 (s) Fluorine F (g) F- (aq) F2 (g) HF (g) Hydrogen 152.3…

Calculate AS° at 25°C for the reaction, 2P6O(s) + C(s) --> 2Pb(s) + Co,(g) given these absolute entropies: S°(J/K•mol) 69.45 РЬО(S) C(s) Pb(s) CO2(g) (Answer to the nearest 0.1 J/K) 5.7 64.89 213.6 Answer:

For a nonspontaneous reaction , AS° = 189 J/K, and AH° = 76.3 KJ. At what temperature this reaction becomes spontaneous ? 520 K 302 K 298 K 404 K

4. Use the given data at 298 K to calculate AS univ, and state whether the reaction occurs spontaneously at this temperature.: 2Cl:(9) + SO:(9) SOCla(g) + Cl20(g) SOC (g) Cl20(g) -212.5 309.77 Substance: Cl2(g) SO2(g) -296.8 AH° (kJ/mol): O S°(J/K-mol): 223.0 80.3 248.1 266.1