AP Chemistry test with answers

FORM B NAME: ト 2-PF AP CHEMISTRY THIRD QUARTER TEST Class Copy 2010 MULTIPLE CHOICE: Place the letter of the best answer in the blank provided. E1) The table shown below contains concentration and rate data for this reaction: A+2B C Determine the rate law for this reaction. Exp Initial A 1 0.17 2 0.17 3 0.51 Initial B Initial rate M/s 0.23 0.33 0.46 2.64 0.23 0.33 a) Rate= k [A] [B] b) Rate= k [B] c) Rate= k [A] d) Rate= k [A] [B] e) Rate= k [B] E2) If the acid dissociation constant, Ka, for an acid HA is 8 e-4 at 25°C, what percent of the acid dissociated in a 0.50 molar solution of HA al 25°C? a) 0.08% b) 0.2% D3) 3) Assume that the reaction described here is second order for both A and B: c) 1% d) 2% e) 4% 4 2A+2B C see What units should you use for the rate constant? 2 a) M¹ sec¹ b) sec c) M² sec d) M³ s e) k has no units D 4) Which one of the following 0.1 M solutions would have the highest pH? a) KCN (Ka HCN = 4.0x1010) d) KCH₂O, (Ka HCH₂O₃ = 3x10) b) NH,NO (Kb NH3= 1.8x10°) e) NaC₂H₃O₂ (Ka HC₂H₃O₂ = 1.8x10) c) NaCIO (Ka HCIO = 3.2x10) D5) 5) What volume of 0.150 molar HCI is required to neutralize 25.0 mL of 0.150 molar Ba(OH)2? a) 25.0 mL b) 30.0 mL c) 40.0 mL d) 50.0 mL e) 80.0 mL E6) HSO + H₂O H₂O + SO 2 In the equilibrium represented above, the species that act as bases include which of the following? ISO a) ii only d) I and ill AP CHEMISTRY THIRD QUARTER TEST II. H₂O b) III only e) II and III III. SO c) I and II B 7) A 1 molar solution of which of the following salts has the highest pH? a) NaNO3 d) NaHSO b) Na₂CO₃ e) Na2SO4 c) NH CI A 8) A solution of calcium hypochlorite, a common additive to swimming pool water, is a) basic because of the hydrolysis by OCI b) basic because Ca(OH), is a weak and insoluble base c) neutral if the concentration is kept below 0.1 Molar d) acidic because of the hydrolysis by the Ca" ions e) acidic because of the acid HOCI is formed B9) All of the following reactions can be defined as Lewis acid-base reactions except a) Al(OH)3 + OH → Al(OH)4 d) NH4+ NH2 → 2 NH b) Cl2 + H2O HOCI+ H+ Cre) H'NH, NH c) SnCl4+ 2Cl→ SnC 2 E10) HCI > HC₂H₂O₂ > HCN > H₂O> NH Five acids are listed above in the order of decreasing acid strength. Which of the following reaction must have an equilibrium constant with a value less than 1? a) HCI + CN HCN + CI d) H2O + NH2NH3 + OH b) HCI+ H₂O H₂O CI e) HCN C₂H₃O₂→ HC₂H₃O₂ + CN c) HC₂H₃O₂ + OH C₂H₃O₂ + H₂O C_11) 11) H₂C₂O +2 H₂O 2 H₂O + C2O Oxalic acid H₂C₂O, is diprotic acid with Ka1 = 5.4 e-2 and Ka2 = 5.3 e-5. For the reaction above, what is the equilibrium constant? a) 5.36 e-2 b) 5.3 e-5 c) 2.8 e-6 d) 1.9 e-10 e) 1.9 e-13 D 12) Write the expression relating solubility to Ksp for silver sulfide (Ag'S). a) Ksp/2 b) Ksp/4 c) Ksp/4 d) ³ Ksp/4 e) Ksp/2 AP CHEMISTRY THIRD QUARTER TEST B13) 13) Estimate the pH at the equivalence point of 34.5 mL of 0.120 M ammonia being titrated with 0.150 M HCI. a) 2 b) 5 c) 7 C14) CH(g) + 20₂(g) → 2H2O(l) + CO₂ d) 9 e) 12 ΔΗ = -889.1 KJ 889571 ΔΗΓΟ Η₂Ο(1) = -285.8 kj/mol AH CO2(g) = -393.3 kj/mol 664 What is the standard heat of formation of methane, AHfCH(g) as calculated from the data above a)-210.0 kj/mol c)-75.8 kj/mol e) 210.0 kj/mol b)-107.5 kj/mol d) 75.8 kj/mol C 15) When solid NH SCN is mixed with solid Ba(OH)2 in a closed container, the temperature drops a gas is produced. Which of the following indicates the correct signs for AG, AH, and AS for this process? a) AG ΔΗ AS b) c) d) e) E16) Which of the following is true for any substance that is boiling. a) AS <0 c) AH - TAG e) AH = TAS b) AH = 0 d) TAS = 0 E17) Of the following reactions, which involves the largest decrease in entropy? a) CaCO3(s) CaO + CO2(g) b) 2 CO(g) + O2 → 2CO2(g) c) Pb(NO3)2(s) + 2KI(s) Pbl2(s) + 2 KNO3(8) d) C3Hg(g) + 502(g) 3 CO2(g) + 4H2O(g) e) 4La(s) + 3O2(g) 2La2O3(s) 18) A steady current of 10 amperes is passed through an aluminum production cell for 15 minutes. Which of the following is the correct expression for calculating the number of grams of aluminum produced? (1 faraday 96,500 coulombs). Al³(aq) + 3e → Al(s) a) (10) (15)(96,500) g (27) (60) c) (10)(15)(60)(27)g (96,500)(3) e) (27)(3) (96,500)(10)(15)(60) b) (10)(15)(27) g (60)(96,500) d) (96,500)(27) g (10)(15)(60)(3) D 19)_Cr2O+(aq) H₂S(g)+ I CY (aq) + S(s) + H₂O(1) Page 3 of 4 AP CHEMISTRY THIRD QUARTER TEST When the equation above is correctly balanced and all coefficients are reduced to lowest whole- number terms, the coefficient for H (aq) is D20 a) 2 b) 4 c) 6 d) 8 e) 14 20) A student pipetted five 25.00 ml. samples of hydrochloric acid and transferred each sample to to an Erlenmeyer flask, diluted it with distilled water, and added a few drops of phenolphthalein to each. Each sample was then titrated with sodium hydroxide solution to the appearance of the first permanent faint pink color. The following results were obtained. 1 sample Volumes of NaOH solution 2nd sample 35.22 mL 3rd sample 36.14 mL 4th sample 36.13 mL 36.15 mL 5th sample 36.12 mL Which of the following is the most probable explanations for the variation in the student's results? a) The burette was not rinsed with NaOH solution. b) The student misread a 5 for a 6 on the burette when the first sample was titrated c) A different amount of water was added to the first sample d) The pipette was not rinsed with the HCl solution e) The student added too little indicator to the first sample 21) 3Cu(s) + 8H(aq) + 2NO, (aq) →3Cu²(aq) + 2NO(g) + 4H2O(1) B21) L Cu(s) acts as an oxidizing agent II. The oxidation state ofnitrogen changes from +5 to +2 Hydrogen ions are oxidized to form H₂O(1) a) I only b) II only c) III only d) I and II e) II and III B 22) The spontaneous reaction that occurs in a voltaic cell: 2 Ag+ Cd(s) 2Ag(s) + Cd² Which of the following occurs when the current is allowed to flow for five minutes? a) Voltage increases b) Voltage decreases but remains above zero c) Voltage becomes zero and remains at zero d) No change in voltage occurs e) Direction of voltage change cannot be predicted without additional information B. 23) Mn(s) + Cu²aq) → Mn²(aq) + Cu(s) A voltaic cell based in the reaction above was constructed from manganese and zinc half cells. The standard cell potential for this reaction was 1.53 volts, but the observed voltage was 1.66 volts. Which of the following could explain this observation? a) The Mn solution was more concentrated than the Cu² solution. b) The Cu² solution was more concentrated than the Mn²* solution c) The manganese electrode was larger than the copper electrode. d) The copper electrode was larger than the manganese electrode. Page 4 of 4