1 A reaction that is spontaneous.

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1 Slide 1 / 55 1 A reaction that is spontaneous. A B C D E is very rapid will proceed without outside intervention is also spontaneous in the reverse direction has an equilibrium position that lies far to the left is very slow

2 Slide 2 / 55 2 A reversible process is one that. A B C D E can be reversed with no net change in either system or surroundings happens spontaneously is spontaneous in both directions must be carried out at low temperature must be carried out at high temperature

3 Slide 3 / 55 3 Which of the following statements is true? A B C D Processes that are spontaneous in one direction are spontaneous in the opposite direction. Processes are spontaneous because they occur at an observable rate. Spontaneity can depend on the temperature. All of the statements are true.

4 Slide 4 / 55 4 Of the following, only is not a state function. A B C D E S H q E T

5 Slide 5 / 55 5 The thermodynamic quantity that expresses the degree of disorder in a system is. A B C D E enthalpy internal energy bond energy entropy heat flow

6 Slide 6 / 55 6 For an isothermal process, ΔS =. A B C D E q q rev / T q rev Tq rev q + w

7 Slide 7 / 55 7 Which one of the following is always positive when a spontaneous process occurs? A B C D E ΔS system ΔS surroundings ΔS universe ΔH universe ΔH surroundings

8 Slide 8 / 55 8 The entropy of the universe is. A B C D E constant continually decreasing continually increasing zero the same as the energy, E

9 Slide 9 / 55 9 The second law of thermodynamics states that. A B C D E ΔE = q + w ΔH rxn = Σ nδh f (products) - Σ mδh f (reactants) for any spontaneous process, the entropy of the universe increases the entropy of a pure crystalline substance is zero at absolute zero ΔS = q rev /T at constant temperature

10 Slide 10 / Which of the following statements is false? A B C D The change in entropy in a system depends on the initial and final states of the system and the path taken from one state to the other. Any irreversible process results in an overall increase in entropy. The total entropy of the universe increases in any spontaneous process. Entropy increases with the number of microstates of the system.

11 Slide 11 / Of the following, the entropy of is the largest. A B C D E HCl (l) HCl (s) HCl (g) HBr (g) HI (g)

12 Slide 12 / Of the following, the entropy of gaseous is the largest at 25 o C and 1 atm. A H 2 B C 2 H 6 C C 2 H 2 D CH 4 E C 2 H 4

13 Slide 13 / True/False: The entropy of a pure crystalline substance at 0 o C is zero.

14 Slide 14 / True/False: The quantity of energy gained by a system equals the quantity of energy gained by its surroundings.

15 Slide 15 / Which one of the following processes produces a decrease in the entropy of the system? A B C D E boiling water to form steam dissolution of solid KCl in water mixing of two gases into one container freezing water to form ice melting ice to form water

16 Slide 16 / ΔS is positive for. A B C D E 2H 2 (g) + O 2 (g) à 2H2O(g) 2NO(g) à N 2 O 4 (g) CO 2 (g) à CO 2 (s) BaF 2 (s) à Ba F - (aq) 2Hg(l) + O 2 (g) à 2HgO(s)

17 Slide 17 / ΔS is positive for. A B C D E CaO(s) + CO 2 (g) à CaCO 3 (s) N 2 (g) + 3H 2 (g) à 2NH 3 (g) 2SO 3 (g) à 2SO 2 (g) + O 2 (g) Ag + (aq) + Cl - (aq) à AgCl(s) H 2 O(l) à H 2 O(s)

18 18 Which reaction produces a decrease in the entropy of the system? Slide 18 / 55 A B C D E CaCO 3 (s) à CaO(s) + CO 2 (g) 2C(s) + O 2 (g) à 2CO(g) CO 2 (s) à CO 2 (g) 2H 2 (g) + O 2 (g) à 2H 2 O(l) H 2 O(l) à H 2 O(g)

19 19 Which reaction produces an increase in the entropy of the system? Slide 19 / 55 A B C D E Ag + (aq) + Cl - (aq) à AgCl(s) CO 2 (s) à CO 2 (g) H 2 (g) + Cl 2 (g) à 2HCl(g) N 2 (g) + 3H 2 (g) à 2NH 3 (g) H 2 O(l) à H 2 O(s)

20 Slide 20 / Which one of the following processes produces a decrease of the entropy of the system? A B C D E dissolving sodium chloride in water sublimation of naphthalene dissolving oxygen in water boiling of alcohol explosion of nitroglycerine

21 21 ΔS is negative for. Slide 21 / 55 A 2SO 2 (g) + O 2 (g) à 2SO 3 (g) B NH 4 Cl(s) à NH 3 (g) + HCl(g) C PbCl 2 (s) à Pb Cl - D 2C(s) + 2O 2 (g) à 2CO 2 (g) E H 2 O(l) à H 2 O(g)

22 Slide 22 / ΔS is negative for. A B C D E 2H 2 O(g) à 2H 2 (g) + O 2 (g) Mg(NO 3 ) 2 (aq) + 2NaOH(aq) à Mg(OH) 2 (s) + 2NaNO 3 (aq) H 2 O(l) à H 2 O(g) C 6 H 12 O 6 (s) à 6C(s) + 6H 2 (g) + 3O 2 (g) NaCl(aq) à Na + (aq) + Cl - (aq)

23 Slide 23 / ΔS is positive for. A B C D E Pb(NO 3 ) 2 (aq) + 2KI(aq) à PbI 2 (s) + 2KNO 3 (aq) 2H 2 O(g) à 2H 2 (g) + O 2 (g) H 2 O(g) à H 2 O(s) NO(g) + O 2 (g) à NO 2 (g) Ag + (aq) + Cl - (aq) à AgCl(s)

24 Slide 24 / Consider a pure crystalline solid that is heated from absolute zero to a temperature above the boiling point of the liquid. Which of the following processes produces the greatest increase in the entropy of the substance? A B C D E melting the solid heating the liquid heating the gas heating the solid vaporizing the liquid

25 25 Slide 25 / 55 The value of ΔSo for the catalytic hydrogenation of acetylene to ethane is J/K mol. C 2 H 2 (g) + H 2 (g) à C 2 H 4 (g) A B C D E -18.6

26 26 Slide 26 / 55 The combustion of acetylene in the presence of excess oxygen yields carbon dioxide and water is shown below. The value of ΔSo for this reaction is J/K mol. 2C 2 H 2 (g) + 5O 2 à 4CO 2 (g) + 2H 2 O(l) A B C D E

27 Slide 27 / The value of ΔSo for the oxidation of carbon to carbon dioxide? C(s, graphite) + O2(g) à CO2(g) A B C D -2.9 E +2.9

28 28 Slide 28 / 55 What is the value of ΔS, in J/K mol, for this reaction: the combustion of ethene in the presence of excess oxygen yielding carbon dioxide and water: C2H4(g) + 3O2(g) à 2CO2(g) + 2H2O(l) A B C D E

29 29 Slide 29 / 55 The combustion of ethane in the presence of excess oxygen yields carbon dioxide and water. The value of ΔSo for this reaction is J/K mol. 2C 2 H 6 (g) + 7O 2 (g) à 4CO 2 (g) + 6H 2 O(l) A B C D E

30 30 Slide 30 / 55 The value of ΔSo for the oxidation of solid elemental sulfur to gaseous sulfur trioxide, as shown below, is J/K mol. 2S(s, rhombic) + 3O 2 (g) à 2SO 3 (g) A B C D E

31 31 Slide 31 / 55 The value of ΔSo for the decomposition of gaseous sulfur trioxide to solid elemental sulfur and gaseous oxygen, as shown below, is J/K mol. 2SO 3 (g) à 2S(s, rhombic) + 3O 2 (g) A B C D E

32 32 Slide 32 / 55 The value of ΔSo for the formation of POCl3 from its constituent elements, as shown below, is J/K mol. P 2 (g) + O 2 (g) + 3Cl 2 (g) à 2POCl 3 (g) A B C D E

33 33 The value of ΔSo for the decomposition of POCl3 into its constituent elements, as shown below is J/K mol. 2POCl 3 (g) à P 2 (g) + O 2 (g) + 3Cl 2 (g) Slide 33 / 55 A B C D E

34 Slide 34 / The value of ΔSo for the formation of calcium chloride from its constituent elements, as shown below, is J/K mol. Ca(s) + Cl 2 (g) à CaCl 2 (s) A B C D E

35 35 Slide 35 / 55 The standard Gibbs free energy of formation of is zero. (I) H 2 O(l) (II) O(g) (III) H 2 (g) A B C D E I only II only III only II and III I, II, and III

36 36 Slide 36 / 55 The standard Gibbs free energy of formation of is zero. (I) H 2 O(l) (II) Na(s) (III) H 2 (g) A B C D E I only II only III only II and III I, II, and III

37 37 Slide 37 / 55 The standard Gibbs free energy of formation of is zero. (I) Al (s) (II) Br 2 (l) (III) Hg (l) A B C D E I only II only III only II and III I, II, and III

38 Slide 38 / The value of ΔGo at 25 o C for the decomposition of gaseous sulfur trioxide to solid elemental sulfur and gaseous oxygen, as shown below, is kj/mol. 2SO 3 (g) à 2S(s, rhombic) + 3O 2 (g) A B C D E

39 39 The value of ΔG o at 25 o C for the decomposition of gaseous sulfur dioxide to solid elemental sulfur and gaseous oxygen,, as shown below, is kj/mol. SO 2 (g) à S(s, rhombic) + O 2 (g) Slide 39 / 55 A B C D E

40 40 The value of ΔG o at 25 o C for the formation of POCl3 from its constituent elements, as shown below, is kj/mol. P 2 (g) + O 2 (g) + 3Cl 2 (g) à 2POCl 3 (g) Slide 40 / 55 A -1,108.7 B +1,108.7 C D E -1,005

41 Slide 41 / The value of ΔGo at 25 o C for the formation of phosphorous trichloride from its constituent elements, as shown below, is kj/mol. P 2 (g) + 3Cl 2 (g) à 2PCl 3 (g) A B C D E

42 Slide 42 / The value of ΔGo at 373 K for the oxidation of solid elemental sulfur to gaseous sulfur dioxide, as shown below, is kj/mol. At 298 K, ΔH o for this reaction is kj/mol, and ΔS o is J/K. S(s, rhombic) + O 2 (g) à SO 2 (g) A B C -4,597 D +4,597 E

43 Slide 43 / With thermodynamics, one cannot determine. A B C D the speed of a reaction the direction of a spontaneous reaction the extent of a reaction the temperature at which a reaction will be spontaneous

44 Slide 44 / For the reaction shown below, ΔHo is +137 kj/mol and ΔS o is +120 J/mol. This reaction is. C 2 H 6 (g) à C 2 H 4 (g) + H 2 (g) A B C D spontaneous at all temperatures spontaneous only at high temperature spontaneous only at low temperature nonspontaneous at all temperatures

45 Slide 45 / A reaction that is not spontaneous at low temperature can become spontaneous at high temperature if ΔH is and ΔS is. A +, + B -, - C +, - D -, + E +, 0

46 Slide 46 / For a reaction to be spontaneous under standard conditions at all temperatures, the signs of ΔH o and ΔS o must be and, respectively. A +, + B +, - C -, + D -, - E +, 0

47 Slide 47 / For the below reaction, ΔHo = kj/mol and ΔS o = J/mol at 298 K. At temperatures greater than C this reaction is spontaneous under standard conditions C(s) + H 2 O(g)à CO(g) + H 2 (g) A 273 B 325 C 552 D 710 E 983

48 Slide 48 / Find the temperature (in K) above which a reaction with a ΔH of kj/mol and a ΔS of J/mol-K becomes spontaneous.

49 Slide 49 / Find the temperature (in K) above which a reaction with a ΔH of kj/mol and a ΔS of J/mol-K becomes spontaneous.

50 Slide 50 / Given the following table of thermodynamic data, complete the following sentence. The vaporization of PCl 3 (l) is. A B C D E nonspontaneous at low temperature and spontaneous at high temperature spontaneous at low temperature and nonspontaneous at high temperature spontaneous at all temperatures nonspontaneous at all temperatures not enough information given to draw a conclusion

51 Slide 51 / Given the following table of thermodynamic data, complete the following sentence. The vaporization of TiCl 4 is. A B C D E spontaneous at all temperatures spontaneous at low temperature and nonspontaneous at high temperature nonspontaneous at low temperature and spontaneous at high temperature nonspontaneous at all temperatures not enough information given to draw a conclusion

52 52 Slide 52 / 55 Given the following table of thermodynamic data, determine the temperature (in C) above which this reaction is nonspontaneous under standard conditions. Ag + (aq) + Cl - (aq) à AgCl(s) A 1230 B 150 C 432 D 133 E 1640

53 53 Slide 53 / 55 Given the following table of thermodynamic data, determine the temperature (in C) above which the reaction is nonspontaneous. NH 3 (g) + HCl(g) à NH 4 Cl(s) A Spontaneous at all temperatures B C D E 1235

54 54 Slide 54 / 55 Given the following table of thermodynamic data, determine the temperature (in C) above which the reaction is nonspontaneous. FeO(s) + Fe(s) + O 2 (g) à Fe 2 O 3 (s) A Spontaneous at all temperatures B C D 2438 E 1235

55 Slide 55 / 55

AP Study Questions

AP Study Questions Class: Date: AP 19.5-19.7 Study Questions Multiple Choice Identify the choice that best completes the statement or answers the question. 3. The value of G at 25 C for the formation of POCl 3 from its constituent