Problem Set 13 Chapter 20 Kotz Electrochemistry etc 1 The half reaction MnO4 aq 8 H aq 5 e Mn2 aq 4 H2O l a is an oxidation half reaction and occurs at the anode b is an oxidation half reaction and occurs at the cathode c is a reduction half reaction and occurs at the anode d is a reduction half reaction and occurs at the cathode 2 When the half reaction NO3 NO is balanced there a are 2 H on the left and 2 H2O on the right b is 1 H on the left and 2 H2O on the right c are 6 H on the left and 3 H2O on the right d are 4 H on the left and 2 H2O on the right e none of the above is the correct answer 3 What is the appropriate shorthand notation for the galvanic cell based on the reaction Zn s Ni NO3 2 aq Zn NO3 2 aq Ni s a Ni2 aq Ni s Fe s Zn 2 aq b Zn s Ni2 aq Zn 2 aq Ni s aq Ni s aq NO3 c Zn s NO3 d Zn s Zn 2 aq Ni2 aq Ni s e Ni s Ni NO3 2 aq Zn NO3 2 aq Zn s 4 The balanced equation for the cell reaction of the galvanic cell Cd s Cd 2 aq Br2 l Br aq Pt is a Cd s 2 Br aq Cd 2 aq Br2 l b Cd s Br2 l Cd2 aq 2 Br aq c Cd 2 aq 2 Br aq PbCl2 s d Cd 2 aq 2 Br aq Cd s Br2 l e Cd 2 aq Br2 l Cd s 2 Br aq 5 Consider the following standard reduction potentials 2H aq 2e H2 g Eo 0 00V Ni2 aq 2e Ni s Eo 0 25V Cd2 aq 2e Cd s Eo 0 40V Which pair of reactants will yield a product favored reaction a Ni2 aq with Cd2 aq with Cd2 aq b Ni s c Ni2 aq with H aq d Cd s e Cd s with Ni s with Ni2 aq 6 According to the following cell diagram which species is getting reduced Sn s Sn 2 aq MnO2 s Mn2 aq Pt a Sn b Sn2 c Pt d MnO2 e Mn2 7 Given that Eo tot 0 460V calculate the cell voltage for 2 Ag aq 0 010M Cu s Cu2 aq 0 10M 2 Ag s a 0 282V b 0 371V c 0 430V d 0 460V e 0 519V 8 Calculate the equilibrium constant K for the reaction Sn s Pb2 aq Sn2 aq Pb s where Eo tot 0 0140V a 0 113 b 8 84 c 1 72 d 2 97 e 0 336 9 For the reaction a removing Br2 l b adding OH aq c increasing Br aq d more than one of the above e none of the above 2 MnO4 aq 10 Br aq 16 H aq 2 Mn2 aq 5 Br2 l 8 H2O l the Eo 0 44V at 25oC The EMF of this reaction can be decreased by 10 For a certain oxidation reduction reaction Eo is positive This means that a delta Go is negative and K is less than 1 b delta Go is negative and K is greater than 1 c delta Go is zero and K is greater than 1 d delta Go is positive and K is greater than 1 e delta Go is positive and K is less than 1 ANSWERS 1 C 2 D 3 D 4 B 5 E 6 D 7 B 8 D 9 B 10 B