Name AP Chemistry September 30, 2013

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1 Name AP Chemistry September 30, 2013 AP Chemistry Exam Part I: 40 Questions, 40 minutes, Multiple Choice, No Calculator Allowed Bubble the correct answer on the blue side of your scantron for each of the following. Use the following answers for questions 1-3. (A) Ar (B) N (C) Mg (D) K (E) Mn 1. This element is unreactive. 2. This element has one valence electron. 3. This element forms polyatomic ions where it loses 7 electrons. 4. A pure sample of KClO 3 is found to contain 142 grams of chlorine atoms. What is the mass of the sample? (A) 244 grams (B) 340 grams (C) 418 grams (D) 494. grams (E) 586 grams 5. The volume of distilled water that should be added to 10.0 m of 5.00 M HCl(aq) in order to prepare a M HCl(aq) solution is approximately (A) 40.0 m (B) 50.0 m (C) 90. m (D) 100. m (E) 110. m 6. A compound contains 1.10 mol of Na, 0.55 mol of S, and 1.65 mol of O. What is the simplest formula of this compound? (A) Na 2 SO 4 (B) NaS 2 O (C) Na 2 SO 3 (D) Na 2 SO 6 (E) Na 4 SO 6 7. Approximately what mass of CuSO 4 5H 2 O (250. g mol -1 ) is required to prepare 250. m of M copper(ii) sulfate solution? (A) g (B) 18.8 g (C) 30.0 g (D) 255 g (E) 420. g CS 2 (l) + 3 O 2 (g) CO 2 (g) + 2 SO 2 (g) 8. What volume of O 2 (g) is required to react with excess CS 2 (l) to produce 2.0 of CO 2 (g)? (Assume all gases are measured at 0 C and 1 atm.) (A) 6 (B) 11.2 (C) 22.4 (D) 44.8 (E) The atomic mass of copper is Given that there are only two naturally occurring isotopes of copper, 63 Cu and 65 Cu, the natural abundance of the 63 Cu isotope must be approximately (A) 90% (B) 75% (C) 50% (D) 25% (E) 10%... Cr 2 O 7 2 (aq) +... H2 S(g) +... H + (aq)... Cr 3+ (aq) +... S(s) +... H 2 O(l) 10. When the equation above is correctly balanced and all coefficients are reduced to lowest whole-number terms, the coefficient for Cr 3+ (aq) is (A) 2 (B) 4 (C) 6 (D) 8 (E) 14 3 Cu(s) + 8 H + (aq) + 2 NO 3 - (aq) 3 Cu 2+ (aq) + 2 NO(g) + 4 H 2 O(l) 11. True statements about the reaction represented above include which of the following? I. Cu(s) acts as a reducing agent. II. The oxidation state of nitrogen changes from +5 to +2. III. Hydrogen ions are oxidized to form H 2 O(l). (A) I only (B) II only (C) III only (D) I and II (E) II and III 2 N 2 H 4 (g) + N 2 O 4 (g) 3 N 2 (g) + 4 H 2 O(g) 12. When 16.0 g of N 2 H 4 (32 g mol -1 ) and 184 g of N 2 O 4 (92 g mol -1 ) are mixed together and react according to the equation above, what is the maximum mass of H 2 O that can be produced? (A) 9.0 g (B) 18 g (C) 36 g (D) 72 g (E) 144 g 2 H 2 O(l) + 4 MnO 4 (aq) + 3 ClO2 (aq) 4 MnO2 (s) + 3 ClO 4 (aq) + 4 OH (aq) 13. According to the balanced equation above, how many moles of ClO 2 (aq) are needed to react completely with 20. m of 0.40 M KMnO 4 solution? (A) mol (B) mol (C) mol (D) mol (E) 0.12 mol

2 14. Which of the following substances is MOST soluble in water? (A) Na 2 CO 3 (B) CaCO 3 (C) BaCO 3 (D) Pb(CO 3 ) 2 (E) Ag 2 CO A 2.00 container will hold about 5.00 g of which of the following gases at 0 C and 1 atm? (A) SO 2 (B) N 2 (C) CO 2 (D) C 4 H 8 (E) NH If 300. m of 0.60 M MgCl 2 (aq) is added to 300. m of distilled water, what is the concentration of Mg 2+ (aq) in the resulting solution? (Assume volumes are additive.) (A) 0.20 M (B) 0.30 M (C) 0.40 M (D) 0.60 M (E) 1.2 M 17. Estimate the mass of CaCl 2 (molar mass = 110.0) required to prepare m of a M solution of this salt. (A) g (B) g (C) g (D) x 10 4 g (E) g 18. When the following half reaction is balanced with the smallest whole number coefficients, it will contain: NO - 3 NO (A) 2e - on the right side (B) 4e - on the left side (C) 2H 2 O on the right side (D) 2H + on the left side (E) a coefficient of 2 for NO 19. How many grams of lead(ii) nitrate [Pb(NO 3 ) 2 ] must be weighed in order to have exactly 3.00 grams of lead atoms? The molar mass of lead nitrate is 331. (A) 4.80 g (B) g (C) 130 g (D) 3.90 g (E) 48.0 g 20. 2MnO SO H + 2Mn SO H 2 O Which of the following statements is true regarding the reaction given above? (A) MnO - 4 is the oxidizing agent (B) H + acts as the oxidizing agent (C) H + is reduced (D) SO 2-3 is reduced (E) MnO - 4 acts as the reducing agent 21. A student examined 3.0 mole of an unknown carbon compound and found that the compound contained 48 grams of carbon, 32 grams of oxygen and 12 grams of hydrogen. Which of the following could be the molecular of the compound? (A) CH 2 O (B) CH 2 OH (C) CH 3 COOH (D) CH 3 CO (E) C 2 H 5 OH 22. How much water must be added to a 50.0 m solution of M HNO 3 to produce a 0.200M solution of HNO 3? (A) 50.0 m (B) 66.0 m (C) 100. m (D) 134 m (E) 150. m 23. Al 2 (CO 3 ) 3 + 6HCl 2AlCl 3 + 3H 2 O + 3CO 2 When m of 6.00 M hydrochloric acid is added to 702 mg of aluminum carbonate (formula mass = 234) according to the above balanced reaction, what is the maximum number of millimoles of CO 2 gas that will be evolved? (A) 9.0 (B) 5.0 (C) 23.0 (D) 6.0 (E) The molecular formula for the hydrated ferric oxide is generally written as Fe 2 O 3 * x H 2 O because the water content in rust can vary. If a 2-molar sample of hydrated ferric oxide is found to contain 108 g of H 2 O, what is the molecular formula of the compound? (A) Fe 2 O 3 * H 2 O (B) Fe 2 O 3 * 3H 2 O (C) Fe 2 O 3 * 6H 2 O (D) Fe 2 O 3 * 10H 2 O (E) Fe 2 O 3 * 12H 2 O 25. Which of the following elements forms a polyatomic anion where it has an oxidation number of +5? (A) K (B) S (C) Se (D) N (E) O ZnS(s) + 3 O 2 (g) 2 ZnO(s) + 2 SO 2 (g) If the reaction above took place at standard temperature and pressure, what was the volume of O 2 (g) required to produce 20.0 grams of ZnO(s)? (A) (20.0)(2) (81.4)(3)(22.4) (D) (B) (20.0)(3)(22.4) (81.4)(2) (20.0)(3) (81.4)(2)(22.4) (E) (C) (81.4)(2)(22.4) (20.0)(3) (20.0)(2)(22.4) (81.4)(3) 27. Balance the following half-reaction for an acid solution using the smallest possible whole number coefficients and entering the proper number of electrons when needed. MnO 2-4 Mn 2+ In the balanced half reaction: (A) there should be 2 electrons on the right side (B) there should be 3 electrons on the right side (C) there should be 4 electrons on the left side (D) there should be 2 electrons on the left side (E) this is not a half-reaction; no electrons are needed

3 28. Balance the following half-reaction for an acid solution using the smallest possible whole number coefficients and entering the proper number of electrons when needed. MnO 2-4 Mn 2+ In the balanced half reaction the hydrogen ions appear as: (A) 2 on the right side (B) 4 on the left side (C) 8 on the left side (D) 4 on the right side (E) 3 on the left side 29. Cr 2 O 2-7 (aq) + 3Sn 2+ (aq) + 14H + (aq) 2Cr 3+ (aq) + 3Sn 4+ (aq) + 7H 2 O Which of the following statements about this reaction is true? (A) dichromate ions are oxidized by Sn(II) ions (B) hydrogen ions are reduced to H 2 O (C) chromium is reduced from +6 to +3 (D) the oxidation state of chromium does not change (E) oxygen is reduced from -2 to IO - 3 (aq) + H + (aq) I 2 (aq) + H 2 O(l) When the above half-reaction is balanced by entering the electrons where needed and using the smallest whole-number coefficients possible, there will be: (A) 10 electrons on the left-hand side (B) no electrons (C) 8 electrons on the right-hand side (D) 3 electrons on the right-hand side (E) 5 electrons on the left hand side 31. The compound that contains 47.1% oxygen is: (A) NaOH (B) CaO (C) Al 2 O 3 (D) BaO (E) Ca(OH) A halogen, X, and an alkali metal, M, can form a compound with the formula: (A) MX (B) MX 2 (C) MX 3 (D) M 2 X 3 (E) M 3 X Which of the following cannot be a reducing agent? (A) Ag + (B) I - (C) Fe 2+ (D) Cr 3+ (E) Cl CH 4 + 2O 2 CO 2 + 2H 2 O If 16 grams of CH 4 reacts with 32 grams of O 2 in the reaction shown above, which of the following will be true? (A) The mass of H 2 O formed will be twice the mass of CO 2 formed. (B) Equal masses of H 2 O and CO 2 will be formed. (C) Equal numbers of moles of H 2 O and CO 2 will be formed. (D) The limiting reagent will be O 2. (E) The limiting reagent will be CH How many grams of NaOH (molar mass = 40.0 g/mol) are contained in 5.00 x 10 2 m of a 0.20 M sodium hydroxide solution? (A) 4.0 g (B) 20. g (C) 50. g (D) 16 g. (E) none of these 36. A beaker contains m of a 0.20 M Pb(NO 3 ) 2 solution. If 50.0 m of a 0.20 M solution of MgCl 2 is added to the beaker, what will be the final concentration of Pb 2+ ions in solution? (A) 0.20 M (B) 0.10 M (C) M (D) M (E) M 37. HCl(aq) + AgNO 3 (aq) AgCl(s) + HNO 3 (aq) One half liter of a 0.40 molar HCl solution is mixed with one-half liter of a 0.80 molar solution of AgNO 3. A reaction occurs forming a precipitate as shown above. If the reaction goes to completion, what is the mass of AgCl produced? (A) 14 grams (B) 28 grams (C) 42 grams (D) 70 grams (E) 84 grams 38. What is the mass ratio of nitrogen to fluorine in a nitrogen trifluoride molecule? (A) 1.0 to 4.1 (B) 2.0 to 4.1 (C) 1.0 to 8.2 (D) 4.1 to 1.0 (E) 1.4 to An ion containing only oxygen and chlorine is 57.4% oxygen by mass. What is the empirical formula? (A) ClO (B) ClO 2 (C) ClO 3 (D) ClO 4 (E) Cl 2 O When excess hydroxide ions were added to 1.0 liter of CaCl 2 solution, Ca(OH) 2 precipitate was formed. If all the calcium ions in the solution were precipitated in 7.4 grams of Ca(OH) 2, what was the initial concentration of the CaCl 2 solution? (A) 0.05 molar (B) 0.10 molar (C) 0.15 molar (D) 0.20 molar (E) 0.30 molar

4 Name AP Chemistry September 30, 2013 AP Chemistry Exam Part II: Essays. Show A work below. Work should be done in a clear and orderly fashion. abel and draw a border around each answer. 4 Essays 40 minutes Calculator Allowed. Essay #1 A sample of ore containing the mineral tellurite,teo 2, was dissolved in acid. The resulting solution was then reacted with a solution of K 2 Cr 2 O 7 to form telluric acid, H 2 TeO 4. The unbalanced chemical equation for the reaction is given below. TeO 2 (s) + Cr 2 O 7 2- (aq) + H + (aq) qe H 2 TeO 4 (aq) + Cr 3+ (aq) + H 2 O(l) (a) Identify the molecule or ion that is being oxidized in the reaction. (b) Give the oxidation number of Cr in the Cr 2 O 7 2- (aq) ion. (c) Give the oxidation number of Te in the H 2 TeO 4 (aq) ion. (d) Balance the chemical equation given above. In a separate reaction iodine reacts with lead(iv) oxide in an acidic environment. I 2 (s) + PbO 2 (s) IO 3 1- (aq) + Pb 2+ (aq) (e) Identify the molecule or ion that is the oxidizing agent the reaction. (f) Balance the chemical equation given above.

5 Essay #2 Suppose that a stable element, atomic number 119, symbol St (sartepium), is discovered. (a) Would St be a metal or a non-metal? Explain/justify your answer. (b) What would be the most likely charge of the St ion in stable ionic compounds? (c) An isotope of St has a mass number of 293. How many neutrons does it have? (d) Write the formula for the compound formed between St and the oxalate ion. (e) Using your solubility rules, would sartepium oxalate be soluble in water? Explain your reasoning.

6 Essay #3: In a chemical reaction 25.0 m of 0.40 M lead(ii) nitrate is added to 15.0 m of 0.80 M sodium carbonate. (a) Write the complete balanced chemical equation for the reaction. (b) Write the net-ionic equation for the reaction. (c) What is the formula of the precipitate? (d) What substance is the limiting reagent? (e) What mass of precipitate formed? (f) Determine the concentration of each ion remaining in solution.

7 Essay #4: Answer the following questions that relate to the analysis of chemical compounds. (a) A compound containing the elements C, H, N, and O is analyzed. When a g sample is burned in excess oxygen, g of CO 2 (g) is formed. (i) Determine the mass, in grams, of C in the g sample of the compound. (ii) When the compound is analyzed for O content only, the mass percent of O is found to be percent. Determine the mass, in grams, of O in the original g sample of the compound. (iii)the combustion analysis showed that grams of water was produced. Calculate the percent of hydrogen in the compound. (iv)determine the mass, in grams, of N in the original g sample of the compound. (v) Determine the empirical formula of the compound.

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