12. A possible mechanism for the overall reaction: Br_2(g) + 2NO_(g)→ 2NOBr_(g) : NO_(g) + Br_2(g) ←→ NOBr_2(g) (fast; rate constant for forward reaction is k₁ and k_-1 for reverse reaction) NOBr_2(g) + NO_(g)→ 2NOBr_2(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[Br_₂]½
(C) (k₂k₁/k_-1)[NO]²[Br₂]
(D)(k₁/k_-1)2[NO]²
(E)k₂[NOBr₂][NO]

 28. Which of the following has the greatest bond strength? (A)B₂(B)O₂⁻(C)CN⁻ (D)O₂⁺(E)H2

9. A salt, MY, crystallizes in a body-centered cubic structure with a Y⁻ anion at each cube corner and an M⁺ cation at the cube center. Assuming that the Y⁻ anions touch each other and the M⁺ cation at the center, and that the radius of Y⁻ is 158 pm, what is the radius of M⁺? (A)65.4 pm(B)116 pm(C)79.0 pm (D)41.1 pm(E)105.3 pm

10. When 0.014 mol of a weak acid HA is dissolved in enough water to make 1.0 L of solution, [H ⁺] is 1.8x10-3 M. Calculate the freezing point of this solution. Assume that the molarity concentration is equal to the molality concentration, and assume ideal behavior. *Kf (H₂O) is 1.86°C∙kg/mol. (A)-0.029°C(B)-0.026°C(C)-0.058°C (D)+0.029°C(E)+0.058°C

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

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

15. Consider the titration of 100.0 mL of 0.250 M aniline (Kb = 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

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