AP® Chemistry Exam #3 | Complete Questions and answers | latest 2025/26.

APpChemistry Exam SECTION I: Multiple Choice Section I of this exam contains 60 multiple-choice questions. Fill in only the circles for numbers 1 through 60 on your answer sheet. Pages containing a periodic table and lists containing equations and constants are also printed in this booklet. Indicate all of your answers to the multiple-choice questions on the answer sheet. No credit will be given for anything written in this exam booklet, but you may use the booklet for notes or scratch work. After you have decided which of the suggested answers is best, completely fill in the corresponding circle on the answer sheet. Use your time effectively, working as quickly as you can without losing accuracy. Do not spend too much time on any one question. Go on to other questions and come back to the ones you have not answered if you have time. It is not expected that everyone will know the answers to all of the multiple-choice questions. Your total score on Section I is based only on the number of questions answered correctly. Points are not deducted for incorrect answers or unanswered questions. At a Glance Total Time 1 hour and 30 minutes Number of Questions 60 Percent of Total Score 50% Writing Instrument Pencil required Electronic Device Calculator allowed 9 Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3DO NOT DETACH FROM BOOK. 1 1 PERIODIC TABLE OF THE ELEMENTS 18 2 H He 1.008 2 ,5 16 17 4.00 3 4 5 6 7 8 9 10 Li Be B C N 0 F Ne 6.94 9.01 10.81 12.01 14.01 16.00 19.00 20.18 16 17 18 Na Mg Al Si p s Cl Ar 22.99 24.30 3 4 5 6 7 8 9 10 11 12 26.98 28.09 30.97 32.06 35.45 39.95 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 39.10 40.08 44.96 47.87 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.38 69.72 72.63 74.92 78.97 79.90 83.80 52 53 54 Rb Sr y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 85.47 87.62 88.91 91.22 92.91 95.95 101.07 102.91 106.42 107.87 112.41 l14.82 118.71 121.76 127.60 126.90 131.29 85 86 Cs Ba 57-71 Hf Ta w Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 132.91 137.33 * 178.49 180.95 183.84 186.21 190.23 192.22 195.08 196.97 200.59 204.38 207.2 208.98 117 1 I 8 Fr Ra 89-103 Rf Db Sg Bh Hs Mt Ds Rg Cn Nb Fl Mc Lv Ts Og *Lanthanoids La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 138.91 140.12 140.91 144.24 150.36 I 5 1.97 157.25 158.93 162.50 164.93 167.26 168.93 173.05 174.97 tActinoids Ac Th Pa u Np Pu Am Cm Bk Cf Es Fm Md No Lr 232.04 231.04 238.03 Unauthorized copying or reuse of any part of this is illegal. 10 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3AP® CHEMISTRY EQUATIONS AND CONSTANTS UNIT SYMBOLS gram, g mole, mol liter, L meter, m second, s hertz, Hz atmosphere, atm millimeter of mercury, mm Hg degree Celsius, °C kelvin, K joule, J volt, V coulomb, C ampere, A UNIT CONVERSIONS 1 hertz = 1 s−1 1 atm = 760 mm Hg = 760 torr K = ° + C 273.15 1 volt = 1 joule 1 coulomb 1 1 ampere = 1 coulomb second METRIC PREFIXES Factor Prefix Symbol 109 giga G 106 mega M 103 kilo k 10−2 centi c 10−3 milli m 10−6 micro μ 10−9 nano n 10−12 pico p ATOMIC STRUCTURE E = h˜ c = °˜ F ˝ q q r coulombic 2 1 2 E = energy ˜ = frequency ° = wavelength F = force q = charge r = separation Planck's constant, h = 6.626 10 J s × −34 Speed of light, c = 2.998 10 m s × 8 1 − Avogadro's number 6.022 10 mol = × 23 1 − GASES, LIQUIDS, AND SOLUTIONS = PV T PV T 1 1 1 2 2 2 PV = nRT P = P × X , where X = moles A A total A A total moles P = P + P + + P ... total A B C = M n m D = m V KE = 1 mv 2 2 M = L solute solution n A = ˜bc P = pressure V = volume T = temperature n = number of moles X = mole fraction m = mass M = molar mass D = density KE = kinetic energy v = velocity M = molarity A = absorbance ˜ = molar absorptivity b = path length c = concentration Gas constant, = = − − − − R 8.314 J mol K 0.08206 L atm K mol 1 1 1 1 STP = 273.15 K and 1.0 atm = Ideal gas at STP 22.4 L mol−1 AP® Chemistry Practice Exam #3 11KINETICS [A] [ t − A]0 = −kt ln[A] l t − n[A]0 = −kt 1 − = kt [A] 1 t [A]0 t = k 0.693 1 2 k = rate constant t = time t hal = f-life 1 2 EQUILIBRIUM K = [C] [D] a b c  d [A] [B] , where A + B C + D c c d a b K = P P P P ( ) ( ) p ( ) ( ) c d a b C D A B Kw 3 = [H O ] + [OH ] − = 1.0 10 at 25 C × −14 ° p 14 pH p Kw = = + OH at 25°C = − pH log[H O 3 +], pOH l = − og[OH−] = + − K [H O ][A ] [HA] a , 3 = − + K [OH ][HB ] b [B] p log , Ka = − Ka pKb = −log Kb K = × K K , w a b p p p Kw = + Ka Kb pH p = K + log [A ] a [HA] − Equilibrium Constants Kc (molar concentrations) K (gas pressures) p Kw (water) Ka (acid) Kb (base) THERMODYNAMICS/ELECTROCHEMISTRY q = mc˛T ˛ = ˛ Hre  action f ˜ H products − ˛ ˜ Hf reactants ˛ = Sre  action p ˜S S roducts −˜ re  actants ˛ = ˛ − Gre  action f ˜ G products ˜˛Gf reactants ˛ ° = ˛ ° − ˛ ° = − = − ° G H T S RT K nFE ln I = q t  E = E − RT nF cell cell ln Q q = heat m = mass c = specific heat capacity T = temperature S° = standard entropy H° = standard enthalpy G° = standard Gibbs free energy R ga = s constant K = equilibrium constant n = number of moles of electrons E° = standard potential I = current (amperes) q = charge (coulombs) t = time (seconds) Q = reaction quotient Faraday's constant, F = 96,485 coulombs / 1 mol e− 12 AP® Chemistry Practice Exam #3CHEMISTRY SECTION I Time—1 hour and 30 minutes 60 Questions Note: For all questions, assume that the temperature is 298 K, the pressure is 1.0 atm, and solutions are aqueous unless otherwise specified. Directions: Each of the questions or incomplete statements below is followed by four suggested answers or completions. Select the one that is best in each case and then fill in the corresponding circle on the answer sheet. 1. The ratio of gases in a mixture of N2( ) g and He( ) g is represented by the following particle diagram. What is the mole fraction of N2 in this sample of gas? (A) 0.33 (B) 0.50 (C) 0.67 (D) 0.80 Trial Completion Time (seconds) 1 37 2 59 2. A student performed an experiment to study the rate of reaction between solid magnesium, Mg( ) s , and aqueous hydrochloric acid, HCl( ) aq . The student conducted two trials under different experimental conditions, using 0.10 mol of Mg( ) s and 1.00 mol of HCl( ) aq in each trial. Which of the following changes in conditions could account for the difference in the time for the reaction to go to completion in trial 1 and trial 2 ? (A) The mixture of reactants was stirred in trial 2, but not in trial 1. (B) The temperature of the hydrochloric acid was higher in trial 2. (C) The concentration of the hydrochloric acid was greater in trial 2. (D) The solid magnesium was a fine powder in trial 1 but a single chunk in trial 2. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 133. Which of the following represents a molecule with a trigonal bipyramidal geometry? (A) (B) (C) (D) 4. The diagram represents a mixture that results when samples of Cl2( ) g and H2( ) g are combined and react, producing HCl( ) g . Which of the following identifies the limiting reactant and provides the best justification? (A) H2, because there is unreacted H2 present. (B) H2, because it has a smaller molar mass than Cl2. (C) Cl2, because there is no unreacted Cl2 present. (D) Cl2, because it has a larger molar mass than H2. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 14 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #35. A rigid container holds 0.50 mol of Ar( ) g and 0.75 mol of O2( ) g . How will the total pressure of the gases in the container and the partial pressure of O2( ) g be affected by the addition of 0.25 mol of He( ) g at constant temperature? (A) Both the total pressure and the partial pressure of O2( ) g will remain constant. (B) Both the total pressure and the partial pressure of O2( ) g will increase. (C) The total pressure will increase, and the partial pressure of O2( ) g will decrease. (D) The total pressure will increase, and the partial pressure of O2( ) g will remain constant. 6. The ideal gas law best describes the properties of which of the following gases at 0 C ° and 1 atm ? (A) O2 (B) CF4 (C) SO2 (D) SF6 7. Gallium, Ga, reacts with chlorine gas to produce gallium(III) chloride. When the equation for the reaction is balanced with lowest whole-number coefficients, the coefficient for gallium is (A) 1 (B) 2 (C) 3 (D) 4 GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 158. The diagram shown represents water molecules ( ) as they interact with two ions, X and Y, in solution. Which of the following best identifies ions X and Y ? X Y A Ba2+ Cl− B Cl− S2− C S2− Na+ D Ba2+ Na+ (A) A (B) B (C) C (D) D GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 16 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3aq aq aq l l g Reaction 1 : NH H NH Reaction 2 : 2 H O 2 H O O 3 4 2 2 2 2 + + ( ) +( ) +( ) ( ) ( ) ( ) → → 9. Which of the following statements about the reactions represented above is true? (A) Reaction 1 cannot be a redox reaction because total charge is conserved. (B) Reaction 1 is a redox reaction because the nitrogen atom transfers electrons to the H+ ion. (C) Reaction 2 cannot be a redox reaction because both the reactant and the products have neutral charge. (D) Reaction 2 is a redox reaction because there is a transfer of electrons between the oxygen atoms. 10. Which of the following compounds has the strongest Coulombic attractions between its ions in the solid state? (A) MgO (B) CaO (C) MgCl2 (D) CaCl2 M 2 ( ) s + HCl(aq) → MCl2 2 ( ) aq + H ( ) g 11. A student weighs a sample of a group 2 metal, M, and adds it to excess HCl( ) aq to react as represented in the equation. The student measures the volume of H2( ) g produced by collecting the gas over water at 1.00 atm and 298 K, and uses the volume to calculate the moles of H2( ) g . Which of the following questions is most likely to be answered as a result of the experiment? (A) What is the value of ΔHrxn  ? (B) What is the density of metal M ? (C) What is the molar mass of metal M ? (D) What is the value of the specific heat of metal M ? GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 1712. The graph shows the potential energy of two atoms as a function of internuclear distance. What is the approximate bond energy? (A) 140 kJ/mol (B) 170 kJ/mol (C) 200 kJ/mol (D) 270 kJ/mol GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 18 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3Half-Reaction E° Ni2+ + 2 e− → Ni −0.28 V Fe 2 2+ + e− → Fe −0.44 V Cr 3 3+ + e− → Cr −0.74 V 13. Based on the reduction potentials in the table, which of the following reactions is thermodynamically favorable? (A) 3 Ni 2 ( ) s + Cr 3 3+( ) aq → Ni 2 2+( ) aq + Cr( ) s (B) 3 Fe 2 ( ) s + Cr 3 3+( ) aq → Fe 2 2+( ) aq + Cr( ) s (C) 3 Ni 2 2+( ) aq + Cr( ) s → 3 Ni 2 ( ) s aq + Cr3+( ) (D) 3 Fe2+( ) aq + 2 Ni 3 Fe 2 ( ) s → ( ) s + Ni2+( ) aq GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 192 HI( ) g → I H 2( ) g + 2( ) g 14. The decomposition of HI( ) g into I2( ) g and H2( ) g is represented by the equation. The reaction is second order with respect to HI( ) g . Assuming all other conditions are held constant, which initial concentration of HI( ) g will result in an initial rate of formation of H2( ) g that is 16 times higher than that in trial 1, as shown in the table? Trial Initial [ ] HI Rate of Formation of H2( ) g 1 0.20 M x 2 ? 16x (A) 0.40 M (B) 0.80 M (C) 1.6 M (D) 3.2 M 15. A pure sample of which of the following compounds has the highest boiling point? (A) LiCl (B) Cl2 (C) PCl3 (D) CCl4 GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 20 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3Questions 16 - 18 refer to the following information. CaC2( ) s + 2 H2O( ) l g → C H 2 2( ) + Ca( ) ( ) OH 2 s ΔH° = −128 kJ / molrxn When a 0.64 g sample of CaC2( ) s (molar mass 64 g / mol) is added to 100. mL of water at 25 C ° in a calorimeter, all of the CaC2( ) s reacts with water as represented by the equation. 16. Which of the following is true of the reaction system when 0.64 g of CaC2( ) s reacts? (A) 1.3 kJ of energy is absorbed. (B) 1.3 kJ of energy is released. (C) 82 kJ of energy is absorbed. (D) 82 kJ of energy is released. 17. Which of the following statements about the thermodynamic favorability of the reaction at 25 C ° is correct? (A) The high activation energy results in the reaction being thermodynamically unfavorable. (B) Only the ΔH° of the reaction contributes to the reaction being thermodynamically favorable. (C) Only the ΔS° of the reaction contributes to the reaction being thermodynamically favorable. (D) Both the ΔH° and the ΔS° of the reaction contribute to the reaction being thermodynamically favorable. 18. At the completion of the reaction, the pH of the product mixture is measured to be above 7. Which of the following can be concluded from this result? (A) Ca OH ( ) ( ) 2 s is slightly soluble in water. (B) C H 2 2( ) g is a proton donor. (C) H O 2 ( ) l is the limiting reactant. (D) The final temperature of the mixture is below 25°C. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 2119. Which of the following lists chemical species in order from largest to smallest radius? (A) S2− O F (B) O O 2− Ne (C) K+ Ar Cl (D) Na Mg Mg 2+ NO g NO g g 1 2 2( ) → ( ) + O2( ) 20. The following graph shows data from an experiment in which NO2( ) g decomposes as represented by the equation. The graph could be used to support which of the following statements? (A) The half-life of the reaction is constant. (B) The magnitude of the rate constant, k, is approximately 10. (C) The unit of the rate constant, k, is s−1. (D) The rate law for the reaction is rate = [ k NO2]2. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 22 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3CO 2 H CH ( ) g + 2( ) g  3OH( ) g ΔH° = −90 kJ/molrxn 21. The system represented by the equation shown is at equilibrium in a rigid container. Which of the following would decrease the amount of the reactant CO( ) g in the container? (A) Increasing the temperature (B) Decreasing the temperature (C) Adding CH OH 3 ( ) g to the container (D) Removing H2( ) g from the container GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 23Questions 22 through 25 refer to the following. The table contains information about four samples of different monoprotic acids with the general formula HA. Sample Volume ( ) mL Concentration ( ) M pH at 25°C 1 10.0 0.10 1.0 2 5.0 0.10 2.3 3 10.0 0.10 4.7 4 20.0 0.10 2.3 22. Which particle drawing best represents a portion of sample 1 ? (Note that water molecules are omitted.) (A) (B) (C) (D) GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 24 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #323. Which sample of acid would require the largest number of moles of NaOH to neutralize it completely? (A) Sample 1 (B) Sample 2 (C) Sample 3 (D) Sample 4 24. Which sample of acid has the smallest value of Ka ? (A) Sample 1 (B) Sample 2 (C) Sample 3 (D) Sample 4 25. Which statement correctly explains why the pH value of sample 3 is the greatest? (A) It has the smallest value of [H O 3 +]. (B) It has the smallest value of [ ] OH− . (C) It has the weakest conjugate base. (D) It is the strongest acid. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 25O2, H2O, C3H8 4 , CF 26. Of the substances listed above, which has the highest boiling point, and why? (A) O2, because its molecules have a double bond between the oxygen atoms. (B) H2O, because hydrogen bonds form between its molecules. (C) C H 3 8, because multiple hydrogen bonds can form between its molecules. (D) CF4, because its molecules have the largest dipole moment, since C−F bonds are highly polar. 2 NO( ) g + Br2( ) g  2 NOBr( ) g 27. Which of the following is the expression for the equilibrium constant, Kc, for the reaction represented by the balanced chemical equation shown? (A) K NO Br c NOBr [ 2] = [ ] [ ] (B) K NOBr c = NO Br [ 2] [ ] [ ] (C) K NO Br c NOBr 2 2 2 [ ] = [ ] [ ] (D) K NOBr c NO Br 2 2 [ 2] = [ ] [ ] GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 26 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #328. Which of the following best explains why the enthalpy change of the reaction represented above is positive? (A) The reaction is endothermic because breaking the O O = bond requires energy. (B) The reaction is endothermic because breaking the O O = bond releases energy. (C) The reaction is exothermic because breaking the O O = bond requires energy. (D) The reaction is exothermic because breaking the O O = bond releases energy. Mass of metal 15 g Initial temperature of metal 80.0°C Mass of water 50. g Initial temperature of water 18.0°C Final temperature of water 20.0°C Specific heat capacity of water 4.18 J /( ) g · °C 29. A calorimetry experiment is conducted to determine the specific heat capacity of a metal. Based on the results shown in the table, what is the specific heat capacity of the metal? (A) 0.042 J / ( ) g · °C (B) 0.35 J / ( ) g · °C (C) 0.46 J / ( ) g · °C (D) 1.39 J / ( ) g · °C 2 SO2( ) g + O2( ) g  2 SO3( ) g −2 K = 2.5 ¥ 10 at 896 K p 30. Samples of SO2( ) g , O2( ) g , and SO3( ) g are placed in a previously evacuated reaction vessel. In the vessel, initially PSO2 is 4.0 atm, PO2 is 10. atm, and PSO3 is 2.0 atm. If the temperature is held constant, which of the following predicts what will happen to PO2 when the reaction represented above occurs and best explains why? (A) PO2 will increase, because Kp 1. (B) PO2 will decrease, because the total number of moles of reactants is less than the number of moles of product, and the reaction will proceed to form more product. (C) PO2 will decrease, because the initial PSO3 is lowest, and the reaction will proceed in the forward direction. (D) PO2 will not change, because the system is already at equilibrium. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 272 PCl3 2 ( ) g + O 2 ( ) ( ) g → POCl3 g 31. At 398 K the reaction shown has a ΔH° of 543 kJ / mol − rxn and a ΔS° of −178 J / ( ) K · molrxn . The reaction is run at both 398 K and 798 K. Which of the following correctly identifies the thermodynamic favorability for the reaction at the two temperatures? (Assume that ΔH° and ΔS° do not change with temperature.) At 398 K At 798 K A Unfavorable Favorable B Unfavorable Unfavorable C Favorable Favorable D Favorable Unfavorable (A) A (B) B (C) C (D) D 32. A student determines the concentration of an NaBr( ) aq solution by adding AgNO3( ) aq until no more AgBr( ) s precipitate is formed. The precipitate is filtered out of the solution and then dried and weighed. The student uses the mass of the precipitate to determine the concentration of the NaBr( ) aq solution. Which of the following could result in the student calculating a concentration of NaBr aq)( that is higher than the actual concentration? (A) The AgBr( ) s was not completely dried before being weighed. (B) Some of the AgBr( ) s fell off the filter paper onto the balance while being weighed. (C) An insufficient amount of AgNO3( ) aq was added, so some NaBr( ) aq was left in solution. (D) The filter paper had a hole in it, and some of the AgBr( ) s precipitate washed through the filter paper. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 28 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3C2 5 H Cl( ) g → C H HCl 2 4( ) g + ( ) g 33. A scientist performed two trials in a study of the decomposition reaction of compound C2 5 H Cl, represented by the equation shown. Based on the data table below, which of the following outcomes will provide the best evidence that the decomposition reaction is first order? C H 2 5Cl 0 ⎡⎣ ⎤⎦ Initial Rate Half-Life Trial 1 1.0 M R1 t1 Trial 2 2.0 M R2 t2 (A) R2 = = R t 1 2 , t1 (B) R2 = π R t 1 2 , t1 (C) R2 π = R t 1 2 , t1 (D) R2 π π R t 1 2 , t1 GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 2934. N2 g)( reacts with F2( ) g in a sealed, rigid container to produce NF3( ) g according to the following balanced equation. N 3 F 2 2( ) g + 2( ) ( ) g → NF3 g The N2( ) g had an initial partial pressure of 1.00 atm, and the F2( ) g had an initial partial pressure of 1.80 atm. Assuming that the reaction goes to completion and the temperature remains constant, what is the maximum partial pressure of NF3( ) g that could be produced? (A) 0.50 atm (B) 1.20 atm (C) 2.00 atm (D) 2.80 atm 35. Both structure 1 and structure 2 shown are needed to describe the N O 2 molecule. Which of the following indicates the better resonance structure and best explains why? (Formal charges are provided in circles on the diagrams.) (A) Structure 1, because it has two double bonds and is therefore more symmetrical. (B) Structure 1, because the negative formal charge is on the more electronegative element. (C) Structure 2, because the triple bond between the two nitrogen atoms is stronger than the double bond. (D) Structure 2, because the negative formal charge is on the more electronegative element. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 30 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #336. A mixture of diethyl ether, ethanoic acid, and hexane is separated using a thin-layer chromatography experiment. The Lewis diagrams of the compounds in the mixture and the results of the experiment are shown. A student determines the identity of the compound in each spot shown. Based on this information, which of the following conclusions can be drawn about the polarity of the stationary phase and mobile phase used in this experiment? Stationary Phase Mobile Phase A Nonpolar Polar B Nonpolar Nonpolar C Polar Polar D Polar Nonpolar (A) A (B) B (C) C (D) D GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 3137. CHF3 has a normal boiling point of −82.1 C ° , and CHCl3 has a normal boiling point of 61.2°C. Which of the following best helps to explain why CHCl3 has a higher boiling point? (A) CHCl3 has dipole-dipole forces, but CHF3 does not. (B) CHCl3 experiences hydrogen bonding, but CHF3 does not. (C) CHCl3 has stronger London dispersion forces than CHF3 does. (D) CHCl3 has stronger covalent bonds than CHF3 does. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 32 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #338. The complete photoelectron spectra for two species, X and Y, are represented above. One of the species is a neutral atom and the other species is a negatively charged ion. Both species have the same electron configuration. Which of the following can be inferred from the spectra? (A) X has a larger nuclear charge than Y has; therefore, X is neutral and Y is negatively charged. (B) X has a larger nuclear charge than Y has; therefore, Y is neutral and X is negatively charged. (C) X has a smaller nuclear charge than Y has; therefore, X is neutral and Y is negatively charged. (D) X has a smaller nuclear charge than Y has; therefore, Y is neutral and X is negatively charged. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 33Container A B C D Pressure 2.0 atm 1.0 atm 1.5 atm 3.0 atm Temperature 200 K 300 K 300 K 200 K Volume 1.0 L 2.0 L 1.0 L 0.50 L 39. Four containers each hold a sample of O2( ) g . Based on the information in the table, which container has the largest number of O2( ) g molecules? (A) A (B) B (C) C (D) D GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 34 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3Compound Lattice Enthalpy ( ) kJ/mol LiF 1030 LiCl 834 MgCl2 SrCl2 2510 2127 40. Lattice enthalpy can be defined as the ΔH° associated with the separation of a solid crystal into gaseous ions. Which of the following statements about lattice enthalpy is consistent with the information in the table above? (A) It increases with the increasing radii of the ions in the compound. (B) It increases with the decreasing radii of the ions in the compound. (C) It increases with the decreasing charge of the ions. (D) It increases with the decreasing electronegativity of the atoms. 41. Which of the following samples contains the greatest percentage of carbon by mass? (A) (B) (C) (D) GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 3542. The reaction NO CO 2 + → NO + CO2 is exothermic. A proposed mechanism for this reaction is shown. NO NO NO NO 2 2 3 + → + (slow) NO CO NO CO 3 + → 2 2 + ( fast) Which of the following energy profiles is most consistent with the exothermic nature of the reaction and the proposed mechanism? (A) (B) (C) (D) GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 36 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #343. Which of the following processes results in a decrease in entropy of a system? (A) A pot of water is boiled. (B) Water is frozen into ice cubes. (C) Carbon dioxide gas is released from a pressurized container into the atmosphere. (D) A container of pressurized carbon dioxide is heated to a higher temperature. C2 5 H OH( ) l + 3 O 2 2( ) g → CO2( ) g + 3 H2O( ) l ΔH° = −1368 kJ/molrxn 44. Based on the reaction and data table shown, what is the value of H  f Δ of C2 5 H OH( ) l ? Substance ΔH f (kJ / mol) CO2( ) g −394 H O 2 ( ) l −286 O2( ) g 0 (A) −688 kJ / mol (B) −278 kJ / mol (C) 278 kJ / mol (D) 688 kJ / mol GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 3745. Two buffers are represented in the diagram. How do the pH and buffer capacity of buffer X compare to those of buffer Y ? (A) Buffer X has the same pH as buffer Y and a smaller buffer capacity than buffer Y. (B) Buffer X has the same pH as buffer Y and the same buffer capacity as buffer Y. (C) Buffer X has a lower pH than buffer Y and a smaller buffer capacity than buffer Y. (D) Buffer X has a higher pH than buffer Y and a larger buffer capacity than buffer Y. 46. The two primary resonance structures for HCO3− are shown. What are the relative lengths of the carbon-to-oxygen bonds in this ion? (A) Bonds y and z are equal in length and longer than bond x. (B) Bonds y and z are equal in length and shorter than bond x. (C) Bonds x and z are equal in length and longer than bond y. (D) All three bonds are equal in length. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 38 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #347. The particle diagram shown represents a mixture of NO2 and N O 2 4 at equilibrium according to the reaction 2 NO2 2 4 ( ) g  N O (g). Which of the following is the value of Kp for the reaction? (Assume that each particle represents a partial pressure of 1.0 atm for that substance.) (A) 0.50 (B) 0.67 (C) 1.5 (D) 2.0 48. Which of the following compounds would be most effective in decreasing the pH when added to a sample of water that has a pH of 10.3 ? (A) KCl (B) NaNO3 (C) NH NO 4 3 (D) NaC2 3 H O2 49. A pure substance begins as a solid at point A and is heated at a constant rate. Which of the following best describes the process occurring from point B to point C on the heating curve shown? (A) The average kinetic energy of the particles in the system is increasing as the substance melts. (B) The average kinetic energy of the particles in the system is increasing as the substance boils. (C) The potential energy of the particles in the system is increasing as the substance melts. (D) The potential energy of the particles in the system is increasing as the substance boils. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 39Substance Cl2 I2 Boiling point ( ) K 239 457 50. The boiling points of two diatomic elements are listed in the table shown. Which statement best explains the observed difference in the boiling points? (A) Iodine has the larger electron cloud, so molecules of I2 are more polarizable. (B) Iodine has the lower electronegativity, so molecules of I2 are more polar. (C) Chlorine has the smaller atomic radius, so molecules of Cl2 contain weaker bonds. (D) Chlorine has the higher electronegativity, so molecules of Cl2 are more polar. 51. The curves in the figure above represent the distribution of the molecular speeds for the gases H2, O2, N2, and CH4 at the same temperature. Which curve corresponds to the distribution for CH4 ? (A) 1 (B) 2 (C) 3 (D) 4 GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 40 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #352. Beaker 1 and beaker 2 each contain 100.0 mL of saturated CuSO4( ) aq and 25.0 g of undissolved CuSO4(s). A 50.0 mL sample of distilled water is added to beaker 2, the contents are stirred for several minutes, and CuSO4( ) s is observed at the bottom of the beaker. After stirring, which of the following is true about the contents of the beakers? (Assume temperature remains constant.) (A) The concentration of CuSO4( ) aq in beaker 2 is less than in beaker 1. (B) The concentration of CuSO4( ) aq in beaker 2 is greater than in beaker 1. (C) The mass of undissolved CuSO4( ) s in beaker 2 is less than in beaker 1. (D) The mass of undissolved CuSO4( ) s in beaker 2 is greater than in beaker 1. GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 41Questions 53 through 55 refer to the following. The curve shows the results of an acid-base titration. 53. Which of the following is closest to the pKa of the acid for which the titration curve is shown? (A) 2 (B) 4 (C) 8 (D) 13 54. In addition to the information provided in the titration curve, what other value is needed to determine the concentration of the acid used in the titration? (A) The molar mass of the acid (B) The density of the acid (C) The volume of the acid (D) The initial temperature of the acid 55. Which of the following molecular equations could represent the reaction used to generate the titration curve? (A) H PO 3 3 4( ) ( ) ( ) ( ) aq + LiOH aq → 3 H O 2 3 l + Li PO4 aq (B) HCl( ) aq + KOH( ) aq → H O 2 ( ) l + KCl( ) aq (C) HF NaOH ( ) aq aq + ( ) ( ) ( ) → H O 2 l + NaF aq (D) HNO NH NH NO 3( ) aq aq + 3( ) ( ) → 4 3 aq GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 42 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #356. Which of the following chemical changes is best represented by the particle diagram shown? (Water molecules are omitted for clarity.) (A) 2 AgNO3( ) aq + MgI2( ) aq → 2 AgI( ) s + Mg(NO3)2( ) aq (B) AgNO KCl AgCl KNO 3( ) aq + ( ) aq → ( ) s + 3( ) aq (C) 2 HCl Ba ( ) aq + (OH)2( ) aq → BaCl2( ) s l + 2 H2O( ) (D) MnSO4 2 ( ) ( ) ( ) ( ) aq + K S aq → MnS aq + K2 4 SO aq GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 4357. A reversible reaction at standard conditions has a negative enthalpy change (ΔH° 0) and a positive entropy change (ΔS° 0). Which of the following must be true for the equilibrium constant, K , and the standard cell potential, E°, for the forward reaction? K E° A Greater than 1 Positive B Greater than 1 Negative C Less than 1 Positive D Less than 1 Negative (A) A (B) B (C) C (D) D 58. A 15.0 g sample of H O 2 ( ) l initially at 20.0°C absorbs 4.60 kJ of heat. The final temperature of the H O 2 ( ) l is closest to which of the following? (Assume the specific heat capacity of H O 2 ( ) l is constant at 4.18 J/ ( ) g·°C .) (A) 20.1°C (B) 36.5°C (C) 73.4°C (D) 93.4°C 59. Which of the following elements has the largest first ionization energy? (A) Be (B) Li (C) Na (D) Mg Mass of Isotope Percent Abundance 185 amu 37% 187 amu 63% 60. A certain element has two naturally occurring isotopes, as shown in the table. The element’s average atomic mass is closest to which of the following? (A) 185.0 amu (B) 185.6 amu (C) 186.3 amu (D) 187.0 amu GO ON TO THE NEXT PAGE. Unauthorized copying or reuse of any part of this is illegal. 44 AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3END OF SECTION I IF YOU FINISH BEFORE TIME IS CALLED, YOU MAY CHECK YOUR WORK ON THIS SECTION. DO NOT GO ON TO SECTION II UNTIL YOU ARE TOLD TO DO SO. ____________________________________________________________________________ MAKE SURE YOU HAVE DONE THE FOLLOWING: • PLACED YOUR AP ID LABEL ON YOUR ANSWER SHEET • WRITTEN AND GRIDDED YOUR AP ID CORRECTLY ON YOUR ANSWER SHEET • TAKEN THE AP EXAM LABEL FROM THE FRONT OF THIS BOOKLET AND PLACED IT ON YOUR ANSWER SHEET Unauthorized copying or reuse of any part of this is illegal. AP® Chemistry Practice Exam #3 AP® Chemistry Practice Exam #3 45