26. A 0.100 g sample of the weak acid HA (molar mass = 100 g/mol) is dissolved in 500 g water. The freezing point of the resulting solution is -0.0056 *C. Calculate the value of Ka for this acid. Assume molarity equals molality in this solution. (The molal freezing point depression constant Kris 1.86 ℃)
(A)
(B)
(C)
(D)
(E)

22. What is the formula for the compound that crystallizes with a cubic closed packed array of sulfur ions, and that contains zinc ions in 12.5% of the tetrahedral holes and aluminum ions in 50% of the octahedral holes? (A) ZnAISA (B) ZnA12S4 (C) ZnAlS2 (D) ZnAl2S2 (E) ZnAl4S8

23. Metal X has a body-centered cubic structure. If the atomic radius of X is R, what is the edge length of the unit cell? (A)2R (B)√2R (C) (D) (E) √3 R

24. Samples of the gases H2(g) and SO2(g) have equal masses and are at the same temperature and pressure. Calculate the ratio of rates of impact with the walls (H2:SO2). (A) 180 (B) 32 (C) 5.6 (D) 1.0

25. Consider the following gas samples:Which of the following statements is NOT TRUE?(A) Assuming identical intermolecular forces in the two samples, sample M should be morenearly ideal than sample N.(B) The root-mean-square velocity of molecules in sample M is twice as large as the root-mean-square velocity of molecules in sample N.(C) The average kinetic energy of the molecules in sample M is twice the average kineticenergy of the molecules in sample N.(D) The fraction of molecules in sample M having kinetic energies greater than some highfixed value is larger than the fraction of molecules in sample N having kinetic energiesgreater than that same high fixed value.(E) The volume of sample M is twice the volume of sample N.

27. Two isomers (A and B) of a given compound dimerize as follows:Both processes are known to be second order in the reactant, and ki is known to be . In a particular experiment A, and B were placed in separate container at 25 ℃,where and . After each reaction had progressed for 3.00 min, [A] = 3.00 [B]. In this case the rate laws are define as follows:The concentration of A2 after 3.00 min is x M. The half-life for the experiment involving B isy s. What are the values of x and y?(A)(B)(C) (D)(E)

28. Given the following two standard reduction potentials,  Determine for the standard reduction potential of the half-reaction (A) -0.33 V (B)-0.036V (C)-0.11V (D)0.11V (E) 0.33 V

29. The observed solubility of the salt MX in 4.0 M strong acid is . The K, value for the acid HX is . Calculate the value of for the salt MX. (A) (B) (C) (D) (E)

30. A galvanic cell is constructed with copper electrodes and in each compartment. In one compartment, , and in the other compartment, . Calculate the potential for this cell at 25  ℃. The standard reduction potential for is +0.34 V. (A) 0.43 V (B) -0.43 V (C) 0.092 V (D) -0.092 V (E) 0.77 V

31. The standard enthalpy of formation of H2O(I) at 300 K is -286 kJ/mol. Calculate the change in internal energy for the following process at 300 K and 1 atm:  2H2O(I)→2H(g)+O2(g) (A) 278.5 kJ (B) 282.3 kJ(C)289.7kJ (D) 564.5 kJ (E) 579.5 kJ

32. A 0.50 M solution of the BHA has a pH of 7.50 at 25 ℃, where B is a weak base and A- is the anion of the weak acid HA. Ifthe K, value for B is , what is the Ke value for HA? (A)(B)(C)(D) (E)