0. Cu (s) + 2Ag + Cu 2+ + 2Ag (s) If the equilibrium constant for the reaction above is 3.7x10 15, which of the following correctly describes the standard voltage, E o and the standard free energy change, G o, for this reaction? (A) E o is positive and G o is negative (B) E o is negative and G o is positive (C) E o and G o are both positive (D) E o and G o are both negative (E) E o and G o are both zero Use the following answers for questions 1 4 (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 A voltaic cell using the following reaction is in operation: 2 Ag + (lm) + Cd(s) 2 Ag(s) + Cd 2+ (l M) 1. A 50ml sample of 2molar Cd(NO 3 ) 2 solution is added to the Cd(NO 3 ) 2 beaker. 2. The silver electrode is made larger. 3. The salt bridge is replaced by a platinum wire. 4. Current is allowed to flow for 5 minutes. 5. Mg + NO 3 + H + Mg 2+ + NH 4 + + H 2 O When the skeleton equation above is balanced and all coefficients reduced to their lowest wholenumber terms, what is the coefficient for H +? (A) 4 (B) 6 (C) 8 (D) 9 (E) 10 6. CrO 2 + OH 2 CrO 4 + H 2 O + e When the equation for the halfreaction above is balanced, what is the ratio Of the coefficients OH /CrO 2? (A) 1:1 (B) 2:1 (C) 3:1 (D) 4:1 (E) 5:1
7. If 0.060 faraday is passed through an electrolytic cell containing a solution of In 3+ ions, the maximum number of moles of In that could be deposited at the cathode is: (A) 0.01 mole (B) 0.02 mole (C) 0.03 mole (D) 0.06 mole (E) 0.18 mole 8. Which of the following species cannot function as an oxidizing agent? 2 (A) Cr 2 O 7 (B) MnO 4 (C) NO 3 (D) S (E) I 9. 6 I + 2 MnO 4 + 4 H 2 O 3 I 2 + 2 MnO 2 + 8 OH Which of the following statements regarding the reaction represented by the above equation is correct? (A) Iodide ion is oxidized by hydroxide ion (B) MnO 4 is oxidized by iodide ion (C) The oxidation number of manganese changes from +7 to +2 (D) The oxidation number of manganese remains the same (E) The oxidation number of iodine changes from 1 to 0 2 10. Cr 2 O 7 + e + H + Cr 3+ + H 2 O When the equation for the half reaction above is balanced with the lowest whole Number coefficients, the coefficient for H 2 O is: (A) 2 (B0 4 (C) 6 (D) 7 (E) 14 11. Fe 2+ + 2e Fe E o = 0.44 volt Ni 2+ + 2e Ni E o = 0.23 volt The standard reduction potentials for two half reactions are given above. Using the Nernst equation for a galvanic cell, what is the equilibrium constant for the reaction: Fe + Ni 2+ Fe 2+ + Ni (A) 1.9 X 10 23 (B) 7.6 X 10 8 (C) 3.6 X 10 3 (D) 1.3 X 10 7 (E) 5.2 X 10 22 12. When acidified K 2 Cr 2 O 7 solution is added to Na 2 S solution, green Cr 3+ ions and free S are formed. When acidified K 2 Cr 2 O 7 solution is added to NaCl, no change occurs. Of the substances involved in these reactions, which is the best reducing agent? (A) K 2 Cr 2 O 7 (B) Na 2 S (C) Cr 3+ (D) S (E) NaCl 13. If a copper sample containing some zinc impurity is to be purified by electrolysis, the anode and the cathode must be which of the following? (A) anode pure Cu, cathode pure Zn (B) anode pure Zn, cathode pure Cu (C) anode pure Cu, cathode impure copper (D) anodeimpure copper, cathodepure copper (E) anode impure copper, cathode pure Zn
14. 2H 2 O + 4MnO 4 + 3 ClO 2 4 MnO 2 + 3 ClO 4 + 4 OH Which species acts as an oxidizing agent in the reaction represented above? (A) H 2 O (B) ClO 4 (C) ClO 2 (D) MnO 2 (E) MnO 4 15. Ag + + AsH 3 + OH Ag + H 3 AsO 3 + H 2 O When the equation above is balanced with the lowest wholenumber Coefficients, the coefficient for OH is: (A)2 (B)4 (C) 5 (D) 6 (E) 7 16. When aqueous solution of NaOH is added to an aqueous solution of potassium dichromate, K 2 Cr 2 O 7, the dichromate ion is converted to: 2 (A) CrO 4 (B) CrO 2 (C) Cr 3+ (D) Cr 2 O 3 (E) Cr(OH) 3 17. Zn + Cu 2+ Zn 2+ + Cu An electrolytic cell based on the reaction represented above was constructed from zinc and copper halfcells. The observed voltage was found to be 1.00 volt instead of the standard cell potential, E o, of 1.10 volts. Which of the following could correctly account for this observation? (A) The copper electrode was larger than the zinc electrode (B) The Zn 2+ electrolyte was Zn(NO 3 ) 2, while the Cu 2+ electrolyte was CuSO 4. (C) The Zn 2+ solution was more concentrated than the Cu 2+ solution. (D) The solutions in the halfcells had different volumes. (E) The salt bridge contained KCl as the electrolyte 18. What is the maximum mass of Cu that could be plated out by electrolyzing aqueous CuCl 2 for 16.0 hours at a constant current of 3.00 amperes? (A) 28 g (B) 57 g (C) 64 g (D) 114 g (E) 128 g 19. A directcurrent power supply of low voltage has lost the markings that indicate which output terminal is positive and which is negative. A chemist suggests that the power supply terminals be connected to a pair of platinum electrodes that dip into 0.1 molar KI solution. Which of the following correctly identifies the polarities of the power supply terminals? (A) A gas will be evolved only at the positive electrode (B) A gas will be evolved only at the negative electrode (C) A brown color sill appear in the solution near the negative electrode (D) A metal will be deposited on the positive electrode (E) None of the methods above will identify the polarities of the power supply.
20. H 2 Se + 4 O 2 F 2 SeF 6 + 2 HF + 4 O 2 Which of the following is true regarding the reaction represented above? (A) The oxidation number of O does not change (B) The oxidation number of H changes from 1 to +1 (C) The oxidation number of F change from +1 to 1 (D) The oxidation number of Se changes from 2 to +6 (E) It is a disproportionation reaction for F 3 21. AlF 6 + 3 e Al + 6 F Which of the following occurs in the reaction? (A) AlF 3 6 is reduced at the cathode (B) Al is oxidized at the anode (C) Aluminum is converted from the 3 oxidation state to the 0 oxidation state (D) F acts as a reducing agent (E) F is reduced at the cathode 22. A steady current of 10 amps is passed through an aluminumproduction cell for 15 minutes. Which of the following is the correct expression for calculating the number of grams of Al produced? ( 1 faraday = 96,500 coulombs) (A) (10)(15)(96,500) (27)(60) (B) (10)(15)(27) (60)(96,500) (C) (10)(15)(60)(27) (96,500)(3) (D) (96,500)(27) (10)(15)(60)93) 23. Li 3 N + H 2 O Li + + OH + NH 3 When the equation above is balanced and all coefficients are reduced to lowest Wholenumber terms, the coefficient for OH is: (A) 1 (B) 2 (C) 3 (D) 4 (E) 6 24. M + 3 Ag + 3 Ag + M 3+ E o = + 2.46 V Ag + + e Ag E o = + 0.80 V According to the information above, what is the standard reduction potential for The halfreaction : M 3+ + 3 e M (A) 1.66V (B) 0.06 V (C) 0.06 V (D) 1.66 V (E) 3.26 V 25.) In which of the following species does sulfur have the same oxidation number as it does in H 2 SO 4? 2 (A) H 2 SO 3 (B) S 2 O 3 (C) S 2 (D) S 8 (E) SO 2 Cl 2
26.) Cr 2 O 7 2 (aq) + H 2 S(g) + H + (aq) Cr 3+ (aq) + S(s) + H 2 O(l) When the equation above is correctly balanced and all coefficients are reduced to the lowest wholenumber terms, the coefficients for H + (aq) is: (a) 2 (b) 4 (c) 6 (d) 8 (e) 14 28.) 3Cu(s) + 8 H + (aq) + 2 NO 3 (aq) 3 Cu 2+ (aq) + 2NO(g) + 2H 2 O(l) The 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 H 2 O(l) (a) I only (b) II only (c) III only (d) I and II (e) II and III 29.) In electroplating of nickel, 0.200 faraday of electrical charge is passed through a solution of NiSO 4. What mass of nickel is deposited? (a) 2.94g (b) 5.87 g (c) 11.7 g (d) 58.7 g (e) 294 g Answers 0 A 1 B 2 D 3 C 4 B 5 E 6 D 7 B 8 E 9 E 10 D 11 D 12 B 13 D 14 E 15 D 16 A 17 C 18 B 19 B 20 D 21 A 22 C 23 C 24 A 25 E 26 D 28 B 29 B