15. Consider the titration of 100.0 mL of 0.250 M aniline (K_b = 3.8x10^-10) with 0.500 M HCl. Calculate the pH of the solution at the stoichiometric point.
(A)-0.85
(B)8.70
(C)2.68
(D)11.62
(E)7.00

11. The kinetics of the reaction A + 3B→ C + 2D were studied and the following results obtained, where the rate law is: -∆[A]/ ∆t = k[A]n [B]m. For a run where [A]0= 1.0x10-3 M and [B]0= 5.0 M, a plot of ln[A] versus t was found to give a straight line with slope = -5.0x10-2 s -1 . For a run where [A]0= 1.0x10-3 M and [B]0= 10.0 M, a plot of ln[A] versus t was found to give a straight line with slope = -7.1x10-2 s -1 . Calculate the value of k (ignore units). (A)11(B)10(C)50 (D)1.1(E)22

12. A possible mechanism for the overall reaction: Br2(g) + 2NO(g)→ 2NOBr(g) : NO(g) + Br2(g) ←→ NOBr2(g) (fast; rate constant for forward reaction is k1 and k-1 for reverse reaction) NOBr2(g) + NO(g)→ 2NOBr2(g) (slow; rate constant is k2) The rate law for formation of NOBr based on this mechanism is rate = ________. (A)k1[NO]½ (B)k1[Br₂]½ (C) (k2k1/k-1)[NO]²[Br₂] (D)(k1/k-1)2[NO]² (E)k2[NOBr2][NO]

13. For the reaction CaCO₃(s) ←→ CaO(s) + CO₂(g), Kp = 1.16 at 800.°C. If a 21.1 gram sample of CaCO₃ is put into a 10.0 L container and heated to 800°C, what percent of the CaCO₃ will react to reach equilibrium? (A)32.3%(B)62.5%(C)83.8% (D)41.9%(E)100.0%

14. What is the pH of a solution prepared by mixing 50.0 mL of 0.300 M HCl with 450.0 mL of 0.400 M HIO₃ ? (Ka of HIO₃ = 0.16) (A)1.52(B)0.80(C)0.72 (D)0.89(E)1.10

16. The Kf for the complex ion Ag(NH₃) 2+ is 1.7x107 . The Ksp for AgCl is 1.6x10-10. Calculate the molar solubility of AgCl in 1.0 M NH₃. (A)5.2x10-2 M(B)4.7x10-2 M(C)2.9x10-3 M (D)1.3x10-2 M(E)3.5x10-2 M 

17. The equilibrium constant K for the dissociation reaction of a molecule X2 X2(g) ←→ 2X(g) was measured as a function of temperature (in Kelvin). A graph of ln K versus 1/T for this reaction gives a straight line with a slope of –1.352x10⁴ and an intercept of 15.59 K. The value of ∆S for this dissociation reaction is: (A)1.875 J/K mol(B)259.2 J/K mol(C)32.4 J/K mol (D)64.81 J/K mol(E)129.6 J/K mol

18. An excess of finely divided iron is stirred up with a solution that contains Cu²⁺ ion, and the system is allowed to come to equilibrium. The solid materials are then filtered off and electrodes of solid copper and solid iron are inserted into the remaining solution. What is the value of the ratio [Fe²⁺]/[Cu²⁺] at 25°C? The following standard reduction potentials apply: (A)1(B)1.3x1026(C)2.5x1026 (D)4.4x10-27(E)8.8x10-27

19. Rubidium–87 decays by beta decay with a half-life of 4.9×1010 years. How many 87Rb atoms are in a moon rock sample that has a rubidium decay rate of 3500 disintegrations per hour? (A)9.0×1016 atoms (B)4.3×10⁻⁴ atoms (C) 2.2×1018 atoms (D)2.5×1014 atoms (E)2.6×1015 atoms

20. What two oxidation states are more frequently observed in the first transition series than in the third? (A)+3 and +7 (B)+2 and +3 (C) +2 and +7 (D)+5 and +6 (E)+2 and +5

21. Give the number of geometrical isomers for the octahedral compound [MA₂B₂C₂], where A, B, and C represent ligands. (A)1(B)2(C)3 (D)5(E)6