AP Chemistry Final

Consider atoms of the following elements. Assume that the atoms are in the ground state. (A) S (B) Ca (C) Ga (D) Sb (E) Br 1. The atom that contains exactly two unpaired elec¬trons 2. The atom that contains only one electron in the highest occupied energy sublevel

1. A 2. C

(A) F (B) S (C) Mg (D) Ar (E) Mn 1. Forms monatomic ions with 2- charge in solu¬tions 2. Forms a compound having the formula KXO4 3. Forms oxides that are common air pollutants and that yield acidic solution in water

1. B 2. E 3. B

(A) CO32- (B) Cr2O72- (C) NH4+ (D) Ba2+ (E) Al3+ Assume that you have an "unknown" consisting of an aqueous solution of a salt that contains one of the ions listed above. Which ion must be absent on the basis of each of the following observations of the "unknown"? 10. The solution is colorless 11. The solution gives no apparent reaction with di¬lute hydrochloric acid. 12. No odor can be detected when a sample of the solution is added drop by drop to a warm solution of sodium hydroxide. 13. No precipitate is formed when a dilute solution of H2SO4 is added to a sample of the solution.

10. B 11. A 12. C

17. In which of the following groups are the three species isoelectronic; i.e., have the same number of electrons? (A) S2-, K+, Ca2+ (B) Sc, Ti, V2+ (C) O2-, S2-, Cl¬- (D) Mg2+, Ca2+, Sr2+ (E) Cs, Ba2+, La3+

17. A

19. In which of the following species does sulfur have the same oxidation number as it does in H2SO4? (A) H2SO3 (B) S2O32- (C) S2- (D) S8 (E) SO2Cl2

19. E

20. A flask contains 0.25 mole of SO2(g), 0.50 mole of CH4(g), and 0.50 mole of O2(g). The total pressure of the gases in the flask is 800 mm Hg. What is the partial pressure of the SO2(g) in the flask? (A) 800 mm Hg (B) 600 mm Hg (C) 250 mm Hg (D) 200 mm Hg (E) 160 mm Hg

20. E

21. In the laboratory, H2(g) can be produced by adding which of the following to 1 M HCl(aq)? I. 1 M NH3(aq) II. Zn(s) III. NaHCO3(s) (A) I only (B) II only (C) III only (D) I and II only (E) I, II, and Ill

21. B

21. When a sample of oxygen gas in a closed con-tainer of constant volume is heated until its abso-lute tem¬pera¬ture is doubled, which of the follow-ing is also dou¬bled? (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

21. B

2 NH3 NH4+ + NH2- 22. In liquid ammonia, the reaction represented above occurs. In the reaction NH4+ acts as (A) a catalyst (B) both an acid and a base (C) the conjugate acid of NH3 (D) the reducing agent (E) the oxidizing agent

22. C

22. 1s2 2s2 2p6 3s2 3p3 Atoms of an element, X, have the electronic con-figu¬ration shown above. The compound most likely formed with magnesium, Mg, is (A) MgX (C) MgX2 (E) Mg3X2 (B) Mg2X (D) MgX3

22. E

23. The density of an unknown gas is 4.20 grams per liter at 3.00 atmospheres pressure and 127˚C. What is the molecular weight of this gas? (R = 0.0821 liter-atm/mole-K) (A) 14.6 (C) 88.0 (E) 138 (B) 46.0 (D) 94.1

23. B

24. A compound contains 1.10 mol of K, 0.55 mol of Te, and 1.65 mol of 0. What is the simplest formula of this compound? (A) KTeO (B) KTe2O (C) K2TeO3 (D) K2TeO6 (E) K4TeO6

24. C

26. According to the rate law for the reaction, an in-crease in the concentration of hydronium ion has what ef¬fect on this reaction? (A) The rate of reaction increases. (B) The rate of reaction decreases. (C) The value of the equilibrium constant in-creases. (D) The value of the equilibrium constant de-creases. (E) Neither the rate nor the value of the equilib-rium constant is changed.

26. A

26. Approximately what mass of CuSO4•5H2O (250 g mol-1) is required to prepare 250 mL of 0.10 M copper(II) sulfate solution? (A) 4.0 g (B) 6.2 g (C) 34 g (D) 85 g (E) 140 g

26. B

2 NO(g) + O2(g) → 2 NO2(g) 27. A possible mechanism for the overall reaction represented above is the following. (1) NO(g) + NO(g) → N2O2(g) slow (2) N2O2(g) + O2(g) → 2 NO2(g) fast Which of the following rate expressions agrees best with this possible mechanism? (A) Rate = k[NO]2 (B) Rate = k[NO][O2] (C) Rate = k [NO]2[O2] (D) Rate = k[NO]2[O2] (E) Rate = k[N2O2][O2]

27. A

28. Of the following compounds, which is the most ionic? (A) SiCl4 (B) BrCl (C) PCl3 (D) Cl2O (E) CaCl2

28. E

(A) CO2 (B) H2O (C) CH4 (D) C2H4 (E) PH3 3. The molecule with only one double bond 4. The molecule with the largest dipole moment 5. The molecule that has trigonal pyramidal geome¬try

3. D 4. B 5. E

31. What volume of O2(g) is required to react with excess CS2(l) to produce 4.0 L of CO2(g)? (Assume all gases are measured at 0˚C and 1 atm.) (A) 12 L (B) 22.4 L (C) 1/3 × 22.4 L (D) 2 × 22.4 L (E) 3 × 22.4 L

31. A

32. Which of the following oxides is a gas at 25˚C and 1 atm? (A) Rb2O (B) N2O (C) Na2O2 (D) SiO2 (E) La2O3

32. B

33. Which of the following indicators is the best choice for this titration? Indicator pH Range of Color Change (A) Methyl orange 3.2 - 4.4 (B) Methyl red 4.8 - 6.0 (C) Bromothymol blue 6.1 - 7.6 (D) Phenolphthalein 8.2 - 10.0 (E) Alizarin 11.0 - 12.4

33. D

36. A sample of a solution of an unknown was treated with dilute hydrochloric acid. The white precipitate formed was filtered and washed with hot water. A few drops of potassium iodide solu¬tion were added to the hot water filtrate and a bright yellow precipitate was produced. The white precipitate remaining on the filter paper was readily soluble in ammonia solution. What two ions could have been present in the unknown? (A) Ag+(aq) and Hg22+(aq) (B) Ag+(aq) and Pb2+(aq) (C) Ba2+(aq) and Ag+(aq) (D) Ba2+(aq) and Hg22+(aq) (E) Ba2+(aq) and Pb2+(aq)

36. B

39. On the basis of the solubility curves shown above, the greatest percentage of which com¬pound can be recovered by cooling a saturated solution of that compound from 90˚C to 30˚C? (A) NaCl (B) KNO3 (C) K2CrO4 (D) K2SO4 (E) Ce2(SO4)3

39. B

39. Equal masses of three different ideal gases, X, Y, and Z, are mixed in a sealed rigid container. If the tem¬perature of the system remains constant, which of the following statements about the par¬tial pres-sure of gas X is correct? (A) It is equal to 1/3 the total pressure (B) It depends on the intermolecular forces of at-trac¬tion 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 be¬tween molecular collisions. (E) It can be calculated with knowledge only of the volume of the container.

39. C

(A) Hydrofluoric acid (B) Carbon dioxide (C) Aluminum hydroxide (D) Ammonia (E) Hydrogen peroxide 4. Is a good oxidizing agent 5. Is used to etch glass chemically 6. Is used extensively for the production of fertiliz¬ers 7. Has amphoteric properties

4. E 5. A 6. D 7. C

40. The geometry of the SO3 molecule is best de-scribed as (A) trigonal planar (D) bent (B) trigonal pyramidal (E) tetrahedral (C) square pyramidal 41. Which of the following molecules has the shortest bond length? (A) N2 (C) Cl2 (E) I2 (B) O2 (D) Br2

40. A

40. An excess of Mg(s) is added to 100. mL of 0.400 M HCl. At 0˚C and 1 atm pressure, what volume of H2 gas can be obtained? (A) 22.4 mL (B) 44.8 mL (C) 224 mL (D) 448 mL (E) 896 mL

40. D

43. The elements in which of the following have most nearly the same atomic radius? (A) Be, B, C, N (D) C, P, Se, I (B) Ne, Ar, Kr, Xe (E) Cr, Mn, Fe, Co (C) Mg, Ca, Sr, Ba

43. E

44. Which of the following properties generally de¬creases across the periodic table from sodium to chlorine? (A) First ionization energy (B) Atomic mass (C) Electronegativity (D) Maximum value of oxidation number (E) Atomic radius

44. E

45. What is the mole fraction of ethanol, C2H5OH, in an aqueous solution that is 46 percent ethanol by mass? (The molar mass of C2H5OH is 46 g; the molar mass of H2O is 18 g.) (A) 0.25 (B) 0.46 (C) 0.54 (D) 0.67 (E) 0.75

45. A

46. The effective nuclear charge experienced by the outermost electron of Na is different than the ef¬fective nuclear charge experienced by the outer¬most electron of Ne. This difference best ac¬counts for which of the following? (A) Na has a greater density at standard condi¬tions than Ne. (B) Na has a lower first ionization energy than Ne. (C) Na has a higher melting point than Ne. (D) Na has a higher neutron-to-proton ratio than Ne. (E) Na has fewer naturally occurring isotopes than Ne.

46. B

47. Which of the following is a correct statement about reaction order? (A) Reaction order can only be a whole number. (B) Reaction order can be determined only from the coefficients of the balanced equation for the reaction. (C) Reaction order can be determined only by experiment. (D) Reaction order increases with increasing temperature. (E) A second-order reaction must involve at least two different compounds as reactants.

47. C

48. Sodium chloride is LEAST soluble in which of the following liquids? (A) H2O (B) CCl4 (C) HF (D) CH3OH (E) CH3COOH

48. B

48. Which of the following ions is the strongest Lewis acid? (A) Na+ (C) CH3COO- (E) Al3+ (B) Cl- (D) Mg2+ 49. Each of the following can act as both a Brönsted acid and a Brönsted base EXCEPT (A) HCO3- (C) NH4+ (E) HS- (B) H2PO4- (D) H2O

48. E

... Cr2O72-(aq) + .. . H2S(g) + ... H+(aq) → ... Cr3+(aq) + ... S(s) + ... H2O(l) 49. When the equation above is correctly balanced and all coefficients are reduced to lowest whole-number terms, the coefficient for H+(aq) is (A) 2 (B) 4 (C) 6 (D) 8 (E) 14

49. D

50. Which of the following represents acceptable lab¬oratory practice? (A) Placing a hot object on a balance pan (B) Using distilled water for the final rinse of a buret before filling it with standardized solu¬tion (C) Adding a weighed quantity of solid acid to a titration flask wet with distilled water (D) Using 10 mL of standard strength phenolph¬thalein indicator solution for titration of 25 mL of acid solution (E) Diluting a solution in a volumetric flask to its final concentration with hot water

50. C

50. Two flexible containers for gases are at the same tem¬perature and pressure. One holds 0.50 gram of hy¬drogen and the other holds 8.0 grams of oxy¬gen. Which of the following statements re-garding 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 con¬tainer 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 en¬ergy of the oxygen molecules. (E) The average speed of the hydrogen molecules is the same as the average

50. E

3 Cu(s) + 8 H+(aq) + 2 NO3-(aq) → 3 Cu2+(aq) + 2 NO(g) + 4 H2O(l) 51. True statements about the reaction represented above include which of the following? I. Cu(s) acts as an oxidizing agent. II. The oxidation state of nitrogen changes from +5 to +2. III. Hydrogen ions are oxidized to form H2O(l). (A) I only (B) II only (C) III only (D) I and II (E) II and III

51. B

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

51. E

52. Propane gas, C3H8, burns in excess oxygen gas. When the equation for this reaction is correctly balanced and all coefficients are reduced to their lowest whole-number terms, the coefficient for O2 is (A) 4 (B) 5 (C) 7 (D) 10 (E) 22

52. B

53. According to the VSEPR model, the progressive decrease in the bond angles in the series of molecules CH4, NH3, and H2O is best accounted for by the (A) increasing strength of the bonds (B) decreasing size of the central atom (C) increasing electronegativity of the central atom (D) increasing number of unshared pairs of electrons (E) decreasing repulsion between hydrogen atoms

53. D

55. A reaction was observed for 20 days and the per¬centage of the reactant remaining after each day was recorded in the table above. Which of the following best describes the order and the half-life of the reaction? Reaction Order Half-life (days) (A) First 3 (B) First 10 (C) Second 3 (D) Second 6 (E) Second 10

55. A

56. The boiling points of the elements helium, neon, argon, krypton, and xenon increase in that order. Which of the following statements accounts for this increase? (A) The London (dispersion) forces increase. (B) The hydrogen bonding increases. (C) The dipole-dipole forces increase. (D) The chemical reactivity increases. (E) The number of nearest neighbors increases.

56. A

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

58. A

(A) PbSO4 (B) CuO (C) KMnO4 (D) KCl (E) FeCl3 6. Is purple in aqueous solution 7. Is white and very soluble in water

6. C 7. D

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

60. E

65. Which of the following substances is LEAST soluble in water? (A) (NH4)2SO4 (B) KMnO4 (C) BaCO3 (D) Zn(NO3)2 (E) Na3PO4

65. C

65. Which of the following species CANNOT func-tion as an oxidizing agent? (A) Cr2O72- (C) NO3- (E) I- (B) MnO4- (D) S

65. E

66. A 2 L container will hold about 4 g of which of the following gases at 0˚C and 1 atm? (A) SO2 (B) N2 (C) CO2 (D) C4H8 (E) NH3

66. C

66. Ca, V, Co, Zn, As Gaseous atoms of which of the elements above are paramagnetic? (A) Ca and As only (D) V, Co, and As only (B) Zn and As only (E) V, Co, and Zn only (C) Ca, V, and Co only

66. D

67. A student wishes to prepare 2.00 liters of 0.100-mo¬lar KIO3 (molecular weight 214). The proper proce¬dure is to weigh out (A) 42.8 grams of KIO3 and add 2.00 kilograms of H2O (B) 42.8 grams of KIO3 and add H2O until the fi¬nal homogeneous solution has a volume of 2.00 liters (C) 21.4 grams of KIO3 and add H2O until the fi¬nal homogeneous solution has a volume of 2.00 liters (D) 42.8 grams of KIO3 and add 2.00 liters of H2O (E) 21.4 grams of KIO3 and add 2.00 liters of H2O

67. B

67. Which of the following describes the changes in forces of attraction that occur as H2O changes phase from a liquid to a vapor? (A) H—O bonds break as H—H and O—O bonds form. (B) Hydrogen bonds between H2O molecules are broken. (C) Covalent bonds between H2O molecules are broken. (D) Ionic bonds between H+ ions and OH- ions are broken. (E) Covalent bonds between H+ ions and H2O molecules become more effective.

67. B

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

69. B

70. Of the following pure substances, which has the highest melting point? (A) S8 (B) I2 (C) SiO2 (D) SO2 (E) C6H6

70. C

73. A 27.0-gram sample of an unknown hydrocarbon was burned in excess oxygen to form 88.0 grams of carbon dioxide and 27.0 grams of water. What is a possible molecular formula of the hydrocar-bon? (A) CH4 (C) C4H3 (E) C4H10 (B) C2H2 (D) C4H6

73. D

(A) Ne (B) Xe (C) O2 (D) CO (E) NO 8. Has an average atomic or molecular speed closest to that of N2 molecules at 0˚C and 1 atm 9. Has the greatest density 10. Has the greatest rate of effusion through a pin¬hole

8. D 9. B 10. A

(A) A network solid with covalent bonding (B) A molecular solid with zero dipole moment (C) A molecular solid with hydrogen bonding (D) An ionic solid (E) A metallic solid 8. Solid ethyl alcohol, C2H5OH 9. Silicon dioxide, SiO2

8.C 9.A

80. For which of the following molecules are reso-nance structures necessary to describe the bond-ing satisfac¬torily? (A) H2S (C) CO2 (E) PF3 (B) SO2 (D) OF2

80. B

82. Step 1. N2H2O2 N2HO2- + H+ (fast equi¬lib¬rium) Step 2. N2HO2- → N2O + OH- (slow) Step 3. H+ + OH- → H2O (fast) Nitramide, N2H2O2, decomposes slowly in aque-ous solution. This decomposition is believed to oc¬cur ac¬cording to the reaction mechanism above. The rate law for the decomposition of nitramide that is consis¬tent with this mechanism is given by which of the following? (A) Rate = k [N2H2O2] (B) Rate = k [N2H2O2] [H+] (C) (D) (E) Rate = k [N2H2O2] [OH-]

82. C

85. A sample of 9.00 grams of aluminum metal is added to an excess of hydrochloric acid. The vol-ume of hy¬drogen gas produced at standard tem-perature and pressure is (A) 22.4 L (C) 7.46 L (E) 3.74 L (B) 11.2 L (D) 5.60 L

85. B