SOLVED

41) One mole of electrons has a charge of: A) 96,485 A B) 1.60 × 10-19 C) 6.02 × 1023 A D) 96,485 C E) 96,485 F 42) An electrolysis is carried out by passing an electric current through a solution of copper sulfate using inert electrodes. This causes: A) Cu to plate out on the negative electrode B) Cu to plate out on the anode C) oxygen to form on the negative electrode D) H2 to form at the negative electrode E) sulfur to form on the positive electrode 43) Choose the INCORRECT completion of the following sentence: “In the electrolysis of water… A) …a direct current must be used.” B) …oxygen is evolved at the cathode.” C) …electrical energy must be supplied continuously because it is an endothermic reaction.” D) …the volume of hydrogen produced is twice the volume of oxygen produced.” E) ….one mole of H2 is produced for each two moles of electrons.” 44) How many coulombs would be needed to deposit all of the Ag+ ion from 600 mL of a solution 0.250 M in Ag+? A) 1.45 × 107 C B) 1.56 × 106 C C) 1.45 × 104 C D) 2.41 × 104 C E) 1.56 × 104 C 45) The following half-reactions are used in the zinc-air battery. Zn(OH)42- (aq) + 2 e- → Zn(s) + 4 OH-(aq)E° = -1.199 V O2(g) + 2 H2O(l) + 4 e- → 4 OH-(aq)E° = +0.401 V How much charge is transferred per gram Zn(s) in this voltaic cell? A) 5.90 × 103 C B) 2.95 × 103 C C) 1.47 × 103 C D) 3.39 × 10-4 C E) 1.69 × 10-4 C 46) Write the net redox reaction that occurs in the galvanic cell. Zn(s) ? Zn+2(aq) ? Pb+2(aq)?Pb(s) A) Pb(s) + Zn(s) → Pb+2(aq) + Zn+2(aq) + 4 e- B) Pb(s) + Zn+2(aq) → Pb+2(aq) + Zn(s) C) Pb+2(s) + Zn+2(s) → Pb(s) + Zn(s) + 4 e- D) Pb+2(aq) + Zn(s) → Zn+2(aq) + Pb(s) E) Pb(s) + Zn(s) + 4 e- → Pb+2(aq) + Zn+2(aq) 47) For the reaction: Mg(s) + 2 AgNO3(aq) → 2 Ag(s) + Mg(NO3)2(aq) Write a voltaic diagram for the reaction. A) Ag(s) | Ag(aq) ? Mg2+(aq) | Mg(s) B) Mg(s) ? Mg2+ ? Ag+ (aq) ? Ag (s) C) Mg(s) ? Mg2+ ? Ag(s) ? Ag+ (aq) D) Ag(aq) ? Ag(s) ? Mg(s) ? Mg2+ (aq) E) Ag(s) ? Mg2+ (aq) ? Ag+ (aq) ? Mg(s) 48) Write the net redox reaction that occurs in the following galvanic cell. Ti(s) ? Ti3+(aq) ? Se2-(aq) ? Se(s) A) Ti(s) + Se2-(aq) + 1 e- → Ti3+(aq) + Se(s) B) 2 Ti(s) + 3 Se(s) → 2 Ti3+(aq) + 3 Se2-(aq) C) Ti(s) + Se(s) → Ti3+(aq) + Se2-(aq) + 1 e- D) 2 Ti3+(aq) + 3 Se(s) → 2 Ti(s) + 3 Se2-(aq) E) 2 Ti3+(aq) + 3 Se(s) + 1 e- → 2 Ti(s) + 3 Se2-(aq) 49) For the reaction: Mg(s) + AgNO3(aq) → Ag(s) + Mg(NO3)2(aq) Ag+(aq) + e- → Ag(s)E° = 0.800 V Mg2+(aq) + 2 e- → Mg(s)E° = -2.356 V For the reaction, determine E° for the cell. A) 1.556 V B) -3.156 V C) 3.156 V D) 0.800 V E) 2.356 V 50) Given the table below predict the numerical value of the standard cell potential for the reaction: 2 Cr(s) + 3 Cu2+(aq) → 2 Cr3+(aq) + 3 Cu(s) Half ReactionE° (volts) (1) Cr3+ + 3 e- → Cr-0.74 (2) Cr3+ + e- → Cr2+-0.41 (3) Cr2O72- + 14 H+ + 6 e- → 2 Cr3+ + 7 H2O1.33 (4) Cu+ + e- → Cu0.52 (5) Cu2+ + 2 e- → Cu0.34 (6) Cu2+ + e- → Cu+0.16 A) 2.50 volts B) 0.417 volts C) -1.08 volts D) 1.08 volts E) -0.40 volts