AP Chem 1984 MC

29. Cu(s) + 2 Ag+ ---> Cu2+ + 2 Ag(s) If the equilibrium constant for the reaction above is 3.7 x 1015, which of the following correctly describes the standard voltage, E°, and the standard free energy change, DG°, for this reaction? (A) E° is positive and DG° is negative. (B) E° is negative and DG° is positive. (C) E° and DG° are both positive. (D) E° and DG° are both negative. (E) E° and DG° are both zero

A

32. The net ionic equation for the reaction between silver carbonate and hydrochloric acid is (A) Ag2CO3(s) + 2 H+ + 2 Cl¯ ---> 2 AgCl(s) + H2O + CO(g) (B) 2 Ag+ + CO32¯ + 2 H+ + 2 Cl¯ ---> 2 AgCl(s) + H2O + CO2(g) (C) CO32¯ + 2 H+ ---> H2O + CO2(g) (D) Ag+ + Cl¯ ---> AgCl(s) (E) Ag2CO3(s) + 2 H+ ---> 2Ag+ + H2CO3

A

38. The radioactive decay of 6-C-14 to 7-N-14 occurs by the process of (A) beta particle emission (B) alpha particle emission (C) positron emission (D) electron capture (E) neutron capture

A

45. The alkenes are compounds of carbon and hydrogen with the general formula CnH2n. If 0.561 gram of any alkene is burned in excess oxygen, what number of moles of H2O is formed? (A) 0.0400 mole (B) 0.0600 mole (C) 0.0800 mole (D) 0.400 mole (E) 0.800 mole

A

52. 3 Ag(s) + 4 HNO3 <===> 3 AgNO3 + NO(g) + 2 H2O The reaction of silver metal and dilute nitric acid proceeds according to the equation above. If 0.10 mole of powdered silver is added to 10. milliliters of 6.0-molar nitric acid, the number of moles of NO gas that can be formed is (A) 0.015 mole (B) 0.020 mole (C) 0.030 mole (D) 0.045 mole (E) 0.090 mole

A

58. Which of the following represents the ground state electron configuration for the Mn3+ ion? (Atomic number Mn = 25) (A) 1s2 2s22p6 3s23p63d4 (B) 1s2 2s22p6 3s23p63d5 4s2 (C) 1s2 2s22p6 3s23p63d2 4s2 (D) 1s2 2s22p6 3s23p63d8 4s2 (E) 1s2 2s22p6 3s23p63d3 4s1

A

83. NH3(g) + 2 CH4(g) + 5/2 O2(g) <===> H2NCH2COOH(s) + 3 H2O(l) At constant temperature, DeltaH, the change in enthalpy for the reaction above is approximately equal to (A) DeltaE - (11/2)RT (B) DeltaE - (7/2)RT (C) DeltaE + RT (D) DeltaE + (7/2)RT (E) DeltaE (11/2)RT

A

84. Which of the following aqueous solutions has the highest boiling point? (A) 0.10 M potassium sulfate, K2SO4 (B) 0.10 M hydrochloric acid, HCl (C) 0.10 M ammonium nitrate, NH4NO3 (D) 0.10 M magnesium sulfalte, MgSO4 (E) 0.20 M sucrose, C12H22O11

A

H3AsO4 + 3I¯ + 2 H3O+ ---> H3AsO3 + I3¯ + H2O The oxidation of iodide ions by arsenic acid in acidic aqueous solution occurs according to the stoichiometry shown above. The experimental rate law of the reaction is: Rate = k [H3AsO4] [I¯] [H3O+] 26. According to the rate law for the reaction, an increase in the concentration of hydronium ion has what effect on this reaction? (A) The rate of reaction increases. (B) The rate of reaction decreases. (C) The value of the equilibrium constant increases. (D) The value of the equilibrium constant decreases. (E) Neither the rate nor the value of the equilibrium constant is changed.

A

*SEE DIAGRAM ON TEST The spontaneous reaction that occurs when the cell above operates is: 2Ag+ + Cd(s) ---> 2 Ag(s) + Cd2+ (A) Voltage increases. (B) Voltage decreases but remains at zero. (C) Voltage becomes zero and remains at zero. (D) No change in voltage occures. (E) Direction of voltage change cannot be predicted without additional information. Which of the above occurs for each of the following circumstances? 17. Current is allowed to flow for 5 minutes

B

21. When a sample of oxygen gas in a closed container of constant volume is heated until its absolute temperature is doubled, which of the following is also doubled? (A) The density of the gas (B) The pressure of the gas (C) The average velocity of the gas molecules (D) The number of molecules per cm3 (E) The potential energy of the molecules

B

42. Metallic copper is heated strongly with concentrated sulfuric acid. The products of this reaction are (A) CuSO4(s) and H2(g) only (B) Cu2+, SO2(g), and H2O (C) Cu2+, H2(g), and H2O (D) CuSO4(s), H2(g), and SO2(g) (E) Cu2+, SO3(g), and H2O

B

46. If 0.060 faraday is passed through an electrolytic cell containing a solution of In3+ ions, the maximum number of moles of In that could be deposited at the cathode is (A) 0.010 mole (B) 0.020 mole (C) 0.030 mole (D) 0.060 mole (E) 0.18 mole

B

53. Which, if any, of the following species is in the greatest concentration in a 0.100-molar solution of H2SO4 in water? (A) H2SO4 molecules (B) H3O+ ions (C) HSO4¯ ions (D) SO42¯ ions (E) All species are in equilibrium and therefore have the same concentrations.

B

69. What is the mole fraction of ethanol, C2H5OH, in an aqueous solution in which the ethanol concentration is 4.6 molal? (A) 0.0046 (B) 0.076 (C) 0.083 (D) 0.20 (E) 0.72

B

*SEE DIAGRAM ON TEST The spontaneous reaction that occurs when the cell above operates is: 2Ag+ + Cd(s) ---> 2 Ag(s) + Cd2+ (A) Voltage increases. (B) Voltage decreases but remains at zero. (C) Voltage becomes zero and remains at zero. (D) No change in voltage occures. (E) Direction of voltage change cannot be predicted without additional information. Which of the above occurs for each of the following circumstances?

C

39. Equal masses of three different ideal gases, X, Y, and Z, are mixed in a sealed rigid container. If the temperature of the system remains constant, which of the following statements about the partial pressure of gas X is correct? (A) It is equal to 1/3 the total pressure (B) It depends on the intermolecular forces of attraction between molecules of X, Y, and Z. (C) It depends on the relative molecular masses of X, Y, and Z. (D) It depends on the average distance traveled between molecular collisions. (E) It can be calculated with knowledge only of the volume of the container.

C

72. A compound is heated to produce a gas whose molecular weight is to be determined. The gas is collected by displacing water in a water-filled flask inverted in a trough of water. Which of the following is necessary to calculate the molecular weight of the gas, but does NOT need to be measured during the experiment? (A) Mass of the compound used in the experiment (B) Temperature of the water in the trough (C) Vapor pressure of the water (D) Barometric pressure (E) Volume of water displaced from the flask

C

33. The pH of 0.1-molar ammonia is approximately (A) 1 (B) 4 (C) 7 (D) 11 (E) 14

D

35. The addition of an oxidizing agent such as chlorine water to a clear solution of an unknown compound results in the appearance of a brown color. When this solution is shaken with the organic solvent, methylene dichloride, the organic solvent layer turns purple. The unknown compound probably contains (A) K+ (B) Br¯ (C) NO3¯ (D) I¯ (E) Co2+

D

59. When 70. milliliter of 3.0-molar Na2CO3 is added to 30. milliliters of 1.0-molar NaHCO3 the resulting concentration of Na+ is (A) 2.0 M (B) 2.4 M (C) 4.0 M (D) 4.5 M (E) 7.0 M

D

63. Acid Acid Dissociation Constant, Ka H3PO4 7 x 10¯3 H2PO4¯ 8 x 10¯8 HPO42¯ 5 x 10¯13 On the basis of the information above, a buffer with a pH = 9 can best be made by using (A) pure NaH2PO4 (B) H3PO4 + H2PO4¯ (C) H2PO4¯ + PO43¯ (D) H2PO4¯ + HPO42¯ (E) HPO42¯ + PO43¯

D

74. How many moles of NaF must be dissolved in 1.00 liter of a saturated solution of PbF2 at 25 °C to reduce the [Pb2+] to 1 x 10¯6 molar? (Ksp of PbF2 at 25 °C = 4.0 x 10¯8) (A) 0.020 mole (B) 0.040 mole (C) 0.10 mole (D) 0.20 mole (E) 0.40 mole

D

81. What is the net ionic equation for the reaction that occurs when aqueous copper(II) sulfate is added to excess 6-molar ammonia? (A) Cu2+ + SO42¯ + 2 NH4+ + 2 OH¯ ---> (NH4)2SO4 + Cu(OH)2 (B) Cu2+ + 4 NH3 + 4 H2O --> Cu(OH)42¯ + 4 NH4+ (C) Cu2+ + 2 NH3 + 2 H2O --> Cu(OH)2 + 2 NH4+ (D) Cu2+ + 4 NH3 --> Cu(NH3)42+ (E) Cu2+ + 2 NH3 + H2O --> CuO + 2 NH4+

D

Assume that you have an "unknown" consisting of an aqueous solution of a salt that contains one of the ions listed above. Which ions must be absent on the basis of each of the following observations of the "unknown"? 13. No precipitate is formed when a dilute solution of H2SO4 is added to a sample of the solution. (A) CO32¯ (B) Cr2O72¯ (C) NH4+ (D) Ba2+ (E) Al3+

D

20. .....Mg(s) + .....NO3¯(aq) +.....H+(aq) --->......Mg2+(aq) + ....NH4+(aq) + ....H2O(l) When the skeleton equation above is balanced and all coefficients reduced to their lowest whole-number terms. what is the coeficient for H+ ? (A) 4 (B) 6 (C) 8 (D) 9 (E) 10

E

22. 1s2 2s22p6 3s23p3 Atoms of an element, X, have the electronic configuration shown above. The compound most likely formed with magnesium, Mg, is (A) MgX (B) Mg2X (C) MgX2 (D) MgX3 (E) Mg3X2

E

37. The molality of the glucose in a 1.0-molar glucose solution can be obtained by using which of the following? (A) Volume of the solution (B) Temperature of the solution (C) Solubility of glucose in water (D) Degree of dissociation of glucose (E) Density of the solution

E

50. Two flexible containers for gases are at the same temperature and pressure. One holds 0.50 gram of hydrogen and the other holds 8.0 grams of oxygen. Which of the following statements regarding these gas samples is FALSE? (A) The volume of the hydrogen container is the same as the volume of the oxygen container. (B) The number of molecules in the hydrogen container is the same as the number of molecules in the oxygen container. (C) The density of the hydrogen sample is less than that of the oxygen sample. (D) The average kinetic energy of the hydrogen molecules is the same as the average kinetic energy of the oxygen molecules. (E) The average speed of the hydrogen molecules is the same as the average speed of the oxygen molecules.

E

51. Pi bonding occurs in each of the following species EXCEPT (A) CO2 (B) C2H4 (C) CN¯ (D) C6H6 (E) CH4

E

60. Which of the following has a zero dipole moment? (A) HCN (B) NH3 (C) SO2 (D) NO2 (E) PF5

E

64. The net ionic equation for the reaction that occurs during the titration of nitrous aicd with sodium hydroxide is (A) HNO2 + Na+ + OH¯ ---> NaNO2 + H2O (B) HNO2 + NaOH ---> Na+ + NO2¯ + H2O (C) H+ + OH¯ --->H2O (D) HNO2 + H2O ---> NO2¯ + H3O+ (E) HNO2 + OH¯ ---> NO2¯ + H2O

E

71. Which of the following reactions does NOT proceed significantly to the right in aqueous solutions? (A) H3O+ + OH¯ ---> 2 H2O (B) HCN + OH¯ ---> H2O + CN¯ (C) Cu(H2O)42+ + 4 NH3 ---> Cu(NH3)42+ + 4H2O (D) H2SO4 + H2O ---> H3O+ + HSO4¯ (E) H2O + HSO4¯ ---> H2SO4 + OH¯

E

79. 5 Fe2+ + MnO4¯ + 8 H+ <===> 5 Fe3+ + Mn2+ + 4 H2O In a titration experiment based on the equation above, 25.0 milliliters of an acidified Fe2+ solution requires 14.0 milliliters of standard 0.050-molar MnO4¯ solution to reach the equivalence point. The concentration of Fe2+ in the original soluiton is (A) 0.0010 M (B) 0.0056 M (C) 0.028 M (D) 0.090 M (E) 0.14 M

E

Hydrogen Halide Normal Boiling Point, °C HF +19 HCl - 85 HBr - 67 HI - 35 The liquefied hydrogen halides have the normal boiling points given above. The relatively high boiling point of HF can be correctly explained by which of the followng? (A) HF gas is more ideal. (B) HF is the strongest acid. (C) HF molecules have a smaller dipole moment. (D) HF is much less soluble in water. (E) HF molecules tend to form hydrogen bonds.

E