AP Chemistry Semester Exam Form A

AP Chemistry Semester Exam Form A 1. 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 PP T = T2 2. 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? (R0.0821 liter-atm/mole-K) (A) 14.6 (C) 88.0 (B) 46.0 (D) 94.1 (E) 138 (1)(3)=4.2(.082) 400 mw 3. 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 4. The geometry of the SO, molecule is best described as A trigonal planar (D) bent (B) trigonal pyramidal (E) tetrahedral 5. Which of the following molecules has the shortest bond length? 10:0 (C) square pyramidal AN (C) Cl₂ (E) 1, (B) O₂ (D) Br₂ 6. 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 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. 7. Which of the following has a zero dipole moment? (A) HCN (C) SO₂ EPF, (B) NH, (D) NO₂ 8. 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 hydrocarbon? (A) CH (C) C,H, (E) CH10 88 44 =2m27= 1.0ml120 18 (B) C₂H₂ (D) CH H3 9. For which of the following molecules are resonance structures necessary to describe the bonding satisfactorily? (A) H₂S (C) CO₂ (E) PF, (B) SO₂ (D) OF₂ 10. 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, NH,NO, (D) 0.10 M magnesium sulfate, MgSO, (E) 0.20 M sucrose, C12H22O11 11. A sample of 9.00 grams of aluminum metal is added to an excess of hydrochloric acid. The volume of hydrogen gas produced at standard temperature and pressure is (A) 22.4 liters (C) 7.46 liters (E) 3.74 liters (B) 1.2 liters (D) 5.60 liters 27 133 mo +3 Als)+ 3H Al+ 3/2H₂ Questions 12-15 refer to the following descriptions of bonding in different types of solids. (A) Lattice of positive and negative ions held together by electrostatic forces (B) Closely packed lattice with delocalized electrons throughout (C) Strong single covalent bonds with weak intermolecular forces (D) Strong multiple covalent bonds (including Pi-bonds) with weak intermolecular forces (E) Macromolecules held together with strong polar bonds A Cesium chloride, CsCl(s) A 13. Gold, Aus) B 14. Carbon dioxide, CO₂(5) 15. Methane, CH (5) C 16. What mass of Au is produced when 0.0500 mol of Au₂S, is reduced completely with excess H₂? (A)9.85 g (B)19.7 g (D)39.4 g (E)48.9 g (C)24.5 g Au₂53+ H₂→ 2Aut $2 05 x 2 = .1 P R ure Q Time 17. The cooling curve for a pure substance as it changes from a liquid to a solid is shown above. The solid and the liquid coexist at (A) point Q only (B) point R only (C) all points on the Curve between Q and S (D) all points on the curve between R and T (E) no point on the curve 18 The melting point of MgO is higher than that of NaF. Explanations for this observation include which of the following? I.Mg is more positively charged than Na". II.O is more negatively charged than F. III. The O² ion is smaller than the F ion. (A)II only (B) and II only (C)I and III only (D)II and III only (E)I, II, and III 19. Types of hybridization exhibited by the C atoms in propene, CH,CHCH₂, include which of the following? H 1 L.sp III. sp³ (A) I only II.sp (B)III only (C) I and II only (DII and III only HH H-C-CC け H (E)I, II, and III 20-If the temperature of an aqueous solution of NaCl is increased from 20 °C to 90 °C which of the following statements is true? (A) The density of the solution remains unchanged. (B) The molarity of the solution remains unchanged. (C) The molality of the solution remains unchanged. (D) The mole fraction of solute decreases.. (E) The mole fraction of solute increases. 21 A 1.0 L sample of an aqueous solution contains 0.10 mol of NaCl and 0.10 mol of CaCl₂. What is the minimum number of moles of AgNO, that must be added to the solution in order to precipitate all of the Cl as AgCl()? (Assume that AgCl is insoluble.). (A)0.10 mol 0.30 mol (E) 0.60 mol (B) 0.20 mol 3 mol Cl L (D) 0.40 mol Ionization Energies for element X (kJ mol) First 580 Second 1,815 Third 2,740 Fourth 11,600 Fifth 14,800 22. The ionization energies for element X are listed in the table above. On the basis of the data, element X is most likely to be (A) Na (B)Mg Al (D)Si (E)P Lawberris (C) Бысгалье (ши н8) D Jeo C E 23. The phase diagram for a pure substance is shown above. Which point on the diagram corresponds to the equilibrium between the solid and liquid phases at the normal melting point? (A)A (D)D (E)E (B)B 24. Of the following molecules, which has the largest dipole moment? (A) CO (B)CO₂ (C)O₂ (DOPIF (E)F, 25. A rigid metal tank contains oxygen gas. Which of the following applies to the gas in the tank when additional oxygen is added at constant temperature? (A) The volume of the gas increases. (B) The pressure of the gas decreases. The average speed of the gas molecules remains the same. (D) The total number of gas molecules remains the same. (E) The average distance between the gas molecules increases. B W+XY+Z 26. Gases W and X react in a closed, rigid vessel to form gases Y and Z according to the equation above. The initial pressure of Wg) is 1.20 atm and that of X(g) is 1.60 atm. No Y(g) or Z(g) is initially present. The experiment is carried out at constant temperature. What is the partial pressure of Z) when the partial pressure of W() has decreased to 1.0 atm? (A)0.20 atm (B)0.40 atm (C)1.0 atm 1.2 1.6 42 (D)1.2 atm (E)1.4 atm 2 1.0 27 On a mountaintop, it is observed that water boils at 90 °C not at 100 °C as at sea level. This phenomenon occurs because on the mountaintop the (A) equilibrium water vapor pressure is higher due to the higher atmospheric pressure (B) equilibrium water vapor pressure is lower due to the higher atmospheric Pressure equilibrium water vapor pressure equals the atmospheric pressure at a lower temperature (D) water molecules have a higher average kinetic energy due to the lower atmospheric pressure (E) water contains a greater concentration of dissolved gases 28 A 40.0 mL sample of 0.25 M KOH is added to 60.0 mL of 0.15 M Ba(OH)2. What is the molar concentration of OH (aq) in the resulting solution? (Assume that the volumes are additive.) (A) 0.10 M (B) 0.19 M (C) 0.28 M 04x.25.01 (D) 0.40 M (E) 0.55 M 106x. 15,004 1019/.12.19 NH₄NO₃(3) N₂O(g) + 2 H₂O(g) 29 A 0.03 mol sample of NH,NO₂(s) is placed in a 1 L evacuated flask, which is then sealed and heated. The NH,NO,(s) decomposes completely according to the balanced equation above. The total pressure in the flask measured at 400 K is closest to which of the following? (The value of the gas constant, R, is 0.082 L atm mol K¹.) 3 atm (B)1 atm (C)0.5 atm (XP)=.09.082X400) (D)0.1 atm (E)0.03 atm C₂H(g) + 3O2(g) →2 CO₂)+2H₂O(g) -1,323 KJ 30. For the reaction of ethylene represented above, AH is -1,323 kJ. What is the value of AH if the combustion produced liquid water H₂O), rather than water vapor H₂O(g)? (AH for the phase change H₂O(g) → H₂O) is-44 kJ mol¹.) (A)-1,235 kJ (B)-1,279 kJ (C)-1,323 kJ (D)-1,367 kJ (E-1,411 kJ 31 Equal numbers of moles of He(g), Ar(g), and Ne(g) are placed in a glass vessel at room temperature. If the vessel has a pinhole-sized leak, which of the following will be true regarding the relative values of the partial pressures of the gases remaining in the vessel after some of the gas mixture has effused? APP

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