Name: Class: Date: Unit 19 Practice Multiple Choice Identify the choice that best completes the statement or answers the question. 1) The first law of thermodynamics can be given as. A) E = q + w B) = C) for any spontaneous process, the entropy of the universe increases D) the entropy of a pure crystalline substance at absolute zero is zero E) S = qrev/t at constant temperature 2) Of the following, only is not a state function. A) S B) H C) q D) E E) T 3) A reversible process is one that. A) can be reversed with no net change in either system or surroundings B) happens spontaneously C) is spontaneous in both directions D) must be carried out at low temperature E) must be carried out at high temperature 4) The thermodynamic quantity that expresses the extent of randomness in a system is. A) enthalpy B) internal energy C) bond energy D) entropy E) heat flow 5) The second law of thermodynamics states that. A) E = q + w B) H rxn = n H f (products) m H f (reactants) C) for any spontaneous process, the entropy of the universe increases D) the entropy of a pure crystalline substance is zero at absolute zero E) S = q rev /T at constant temperature 6) Which one of the following correctly indicates the relationship between the entropy of a system and the number of different arrangements, W, in the system? A) S = kw B) S = C) S = D) S = k lnw E) S = Wk 1
Name: 7) S is positive for the reaction. A) CaO (s) + CO 2 (g) CaCO 3 (s) B) N2 (g) + 3H 2 (g) 2NH 3 (g) C) 2SO 3 (g) 2SO 2 (g) + O 2 (g) D) Ag + (aq) + Cl (aq) AgCl (s) E) H 2 O (l) H 2 O (s) 8) Which reaction produces an increase in the entropy of the system? A) Ag + (aq) + Cl (aq) AgCl (s) B) CO 2 (s) CO 2 (g) C) H 2 (g) + Cl 2 (g) 2 HCl (g) D) N 2 (g) + 3 H 2 (g) 2 NH 3 (g) E) H 2 O (l) H 2 O (s) 9) The equilibrium position corresponds to which letter on the graph of G vs. f (course of reaction) below? A) A B) B C) C D) D E) E 10) Given the following table of thermodynamic data, complete the following sentence. The vaporization of TiCl 4 is. A) spontaneous at all temperatures B) spontaneous at low temperature and nonspontaneous at high temperature C) nonspontaneous at low temperature and spontaneous at high temperature D) nonspontaneous at all temperatures E) not enough information given to draw a conclusion 11) With thermodynamics, one cannot determine. A) the speed of a reaction B) the direction of a spontaneous reaction C) the extent of a reaction D) the value of the equilibrium constant E) the temperature at which a reaction will be spontaneous 2
Name: Use the table below to answer the questions that follow. Thermodynamic Quantities for Selected Substances at 298.15 K (25 C) Substance H f (kj/mol) G f (kj/mol) S (J/K-mol) Carbon C (s, diamond) 1.88 2.84 2.43 C (s, graphite) 0 0 5.69 C 2 H 2 (g) 226.7 209.2 200.8 C 2 H 4 (g) 52.30 68.11 219.4 C 2 H 6 (g) 84.68 32.89 229.5 CO (g) 110.5 137.2 197.9 CO 2 (g) 393.5 394.4 213.6 Hydrogen H 2 ( g) 0 0 130.58 Oxygen O 2 (g) 0 0 205.0 H 2 O (l) 285.83 237.13 69.91 12) The value of S for the reaction 2C (s, diamond) + O 2 (g) 2CO (g) is J/K mol. A) 185.9 B) +185.9 C) 9.5 D) +9.5 E) 195.7 13) The value of S for the oxidation of carbon to carbon dioxide, C (s, graphite) + O 2 (g) CO 2 (g) is J/K mol. The combustion of carbon, as in charcoal briquettes, in the presence of abundant oxygen produces carbon dioxide. A) +424.3 B) +205.0 C) 205.0 D) 2.9 E) +2.9 3
Name: 14) The value of S for the oxidation of solid elemental sulfur to gaseous sulfur trioxide, 2S (s, rhombic) + 3O 2 (g) 2SO 3 (g) is J/K mol. A) +19.3 B) 19.3 C) +493.1 D) 166.4 E) 493.1 15) The value of S for the formation of POCl 3 from its constituent elements, P 2 (g) + O 2 (g) + 3Cl 2 (g) 2POCl 3 (g) is J/K mol. A) 442.0 B) +771.0 C) 321.0 D) 771.0 E) +321.0 16) The value of S for the formation of phosphorous trichloride from its constituent elements, P 2 (g) + 3Cl 2 (g) 2PCl 3 (g) is J/K mol. A) 311.7 B) +311.7 C) 263.6 D) +129.4 E) 129.4 17) The value of H for the oxidation of solid elemental sulfur to gaseous sulfur dioxide, S (s, rhombic) + O 2 (g) SO 2 (g) is kj/mol. A) +269.9 B) 269.9 C) +0.00 D) 11.6 E) +11.6 4
Name: 18) The value of H for the formation of phosphorous trichloride from its constituent elements, P 2 (g) + 3Cl 2 (g) 2PCl 3 (g) is kj/mol A) 288.1 B) +432.4 C) 720.5 D) +720.5 E) 432.4 19) The value of G at 25 C for the oxidation of solid elemental sulfur to gaseous sulfur trioxide, 2S (s, rhombic) + 3O 2 (g) 2SO 3 (g) is kj/mol. A) +740.8 B) 370.4 C) +370.4 D) 740.8 E) +185.2 20) The value of G at 25 C for the formation of POCl 3 from its constituent elements, P 2 (g) + O 2 (g) + 3Cl 2 (g) 2POCl 3 (g) is kj/mol. A) 1108.7 B) +1108.7 C) 606.2 D) +606.2 E) 1,005 21) The value of G at 25 C for the formation of calcium chloride from its constituent elements, Ca (s) + Cl 2 (g) CaCl 2 (s) is kj/mol. A) 795.8 B) +795.8 C) +763.7 D) +748.1 E) 748.1 5
Name: 22) Given the thermodynamic data in the table below, calculate the equilibrium constant (at 298 K) for the reaction: 2 SO 2 (g) + O 2 (g) 2 SO 3 (g) A) 2.40 10 24 B) 1.06 C) 1.95 D) 3.82 10 23 E) More data are needed. 23) Consider the reaction: FeO (s) + Fe (s) + O 2 (g) Fe 2 O 3 (s) Given the following table of thermodynamic data at 298 K: The value K for the reaction at 25 C is. A) 370 B) 5.9 10 4 C) 3.8 10 14 D) 7.1 10 85 E) 8.1 10 19 24) The normal boiling point of C 2 Cl 3 F 3 is 47.6 C and its molar enthalpy of vaporization is 27.49 kj/mol. What is the change in entropy in the system in J/K when 28.6 grams of C 2 Cl 3 F 3 vaporizes to a gas at the normal boiling point? A) 13.1 B) 4.19 C) 4.19 D) 13.1 E) 27.5 25) Of the following, the entropy of is the largest. A) HI (g) B) HBr (g) C) HCl (g) D) HCl (s) E) HCl (l) 6
Name: 26) The standard Gibbs free energy of formation of is zero. (a) H 2 O (l) (b) O (g) (c) Cl 2 (g) A) (a) only B) (b) only C) (c) only D) (b) and (c) E) (a), (b), and (c) 27) The value of G at 181.0 C for the formation of calcium chloride from its constituent elements: Ca (s) + Cl 2 (g) CaCl 2 (s) is kj/mol. At 25.0 C for this reaction, ÄH is 795.8 kj/mol, G is 748.1 kj/mol, and S is 159.8 J/K. A) 868.4 B) 723.2 C) 7.18 10 4 D) 766.9 E) 2.81 10 4 28) For a given reaction, H = 24.2 kj/mol and S = 55.5 J/K-mol. The reaction will have G = 0 at K. Assume that H and S do not vary with temperature. A) 436 B) 2293 C) 298 D) 2.29 E) 0.436 29) For a given reaction with H = 28.1 kj/mol, the G = 0 at 372 K. The value of S must be J/K-mol, assuming that H and S do not vary with temperature. A) 75.5 B) 75.5 C) 7.55 10 5 D) 7.55 10 5 E) 1.32 10 2 7
Name: 30) In the Haber process, ammonia is synthesized from nitrogen and hydrogen: N 2 (g) + 3H 2 (g) 2NH 3 (g) G at 298 K for this reaction is 33.3 kj/mol. The value of G at 298 K for a reaction mixture that consists of 1.9 atm N2, 2.3 atm H 2, and 0.85 atm NH 3 is. A) 1.0 B) 4.09 10 3 C) 8.62 10 3 D) 118.0 E) 41.9 31) The equilibrium constant for a reaction is 0.38 at 25 C. What is the value of G (kj/mol) at this temperature? A) 2.4 B) 4.2 C) 200 D) 4.2 E) More information is needed. 8
Unit 19 Practice Answer Section MULTIPLE CHOICE 1) ANS: A PTS: 1 DIF: 1 REF: Page Ref: 19.1 OBJ: 19.1; G2 2) ANS: C PTS: 1 DIF: 2 REF: Page Ref: 19.1 OBJ: 19.1; G2 3) ANS: A PTS: 1 DIF: 2 REF: Page Ref: 19.1 OBJ: 19.1; G2 4) ANS: D PTS: 1 DIF: 1 REF: Page Ref: 19.2 OBJ: 19.2; G2 5) ANS: C PTS: 1 DIF: 1 REF: Page Ref: 19.2 OBJ: 19.2; G2 6) ANS: D PTS: 1 DIF: 3 REF: Page Ref: 19.3 OBJ: 19.3; G2 7) ANS: C PTS: 1 DIF: 2 REF: Page Ref: 19.4 OBJ: 19.4; G2 8) ANS: B PTS: 1 DIF: 2 REF: Page Ref: 19.4 OBJ: 19.4; G2 9) ANS: C PTS: 1 DIF: 2 REF: Page Ref: 19.5 OBJ: 19.5; G3 10) ANS: C PTS: 1 DIF: 3 REF: Page Ref: 19.6 OBJ: 19.6; G3 11) ANS: A PTS: 1 DIF: 2 REF: Page Ref: 19.7 OBJ: 19.6; G2 12) ANS: B PTS: 1 DIF: 2 REF: Page Ref: 19.4 OBJ: 19.4; G3 13) ANS: E PTS: 1 DIF: 2 REF: Page Ref: 19.4 OBJ: 19.4; G3 14) ANS: D PTS: 1 DIF: 2 REF: Page Ref: 19.4 OBJ: 19.4; G3 15) ANS: A PTS: 1 DIF: 2 REF: Page Ref: 19.4 OBJ: 19.4; G3 16) ANS: C PTS: 1 DIF: 2 REF: Page Ref: 19.4 OBJ: 19.4; G3 17) ANS: B PTS: 1 DIF: 2 REF: Page Ref: 19.5 OBJ: 19.5; G3 18) ANS: C PTS: 1 DIF: 2 REF: Page Ref: 19.5 OBJ: 19.5; G3 19) ANS: D PTS: 1 DIF: 2 REF: Page Ref: 19.5 OBJ: 19.5; G3 20) ANS: A PTS: 1 DIF: 2 REF: Page Ref: 19.5 OBJ: 19.5; G3 21) ANS: E PTS: 1 DIF: 2 REF: Page Ref: 19.5 OBJ: 19.5; G3 1
22) ANS: A PTS: 1 DIF: 4 REF: Page Ref: 19.7 OBJ: 19.7; G3 23) ANS: D PTS: 1 DIF: 5 REF: Page Ref: 19.7 OBJ: 19.7; G3 24) ANS: D PTS: 1 DIF: 3 REF: Page Ref: 19.2 OBJ: 19.2; G4 25) ANS: A PTS: 1 DIF: 2 REF: Page Ref: 19.4 OBJ: 19.4; G2 26) ANS: C PTS: 1 DIF: 1 REF: Page Ref: 19.5 OBJ: 19.5; G2 27) ANS: B PTS: 1 DIF: 2 REF: Page Ref: 19.5 OBJ: 19.5; G4 28) ANS: A PTS: 1 DIF: 2 REF: Page Ref: 19.6 OBJ: 19.6; G4 29) ANS: A PTS: 1 DIF: 4 REF: Page Ref: 19.6 OBJ: 19.6; G4 30) ANS: E PTS: 1 DIF: 3 REF: Page Ref: 19.7 OBJ: 19.7; G4 31) ANS: A PTS: 1 DIF: 3 REF: Page Ref: 19.7 OBJ: 19.7; G4 2
Unit 19 Practice [Answer Strip] ID : A _ C 7) _ D 14) _ C 18) _ A 1) _ B 8) _ A 15) _ D 19) _ C 2) _ C 9) _ A 3) _ B 12) _ C 16) _ A 20) _ D 4) _ C 10) _ C 5) _ E 13) _ B 17) _ E 21) _ D 6) _ A 11)
Unit 19 Practice [Answer Strip] ID : A _ A 22) _ C 26) _ E 30) _ B 27) _ A 31) _ D 23) _ A 28) _ A 29) _ D 24) _ A 25)