Chapter 20 Practice Questions

1 Chapter 20 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the )The gain of electrons by an element is called )oxidationB)reductionC)sublimationD)frac tionationE)disproportionation1)2)_____ is reduced in the following reaction:Cr2O72 + 6S2O32 + 14H+ 2Cr3+ + 3S4O62 + 7H2OA)S2O32 B)Cr3+C)H+D)Cr2O72 E)S4O62 2)3)_____ is the oxidizing agent in the reaction below. Cr2O72 + 6S2O32 + 14H+ 2Cr3+ + 3S4O62 + 7H2OA)H+B)Cr3+C)S2O32 D)S4O62 E)Cr2O72 3)4)Which substance is serving as the reducing agent in the following reaction?14H+ + Cr2O72 + 3Ni 3Ni2+ + 2Cr3+ + 7H2OA)H2OB)NiC)Cr2O72 D)Ni2+E)H+4)5)Which substance is the reducing agent in the reaction below?

2 Pb + PbO2 + 2H2SO4 2 PbSO4 + 2H2OA)PbSO4B)PbO2C)H2SO4D)PbE)H2O5)6)Wha t is the oxidation number of chromium in Cr2O2 7 ion ?A)+12B)+14C)+6D)+3E)+76)7)What is the oxidation number of potassium in KMnO4?A)+3B)0C)+1D) 1E)+27)18)What is the oxidation number of manganese in the MnO1 4ion?A)+4B)+2C)+7D)+1E)+58)9)What is the oxidation number of manganese in MnO2?A)+2B)+7C)+1D)+4E)+39)10)_____ electrons appear in the following half reaction when it is 2S2O32 A)2B)4C)6D)3E)110)11)The balanced half reaction in which chlorine gas is reduced to the aqueous chloride ion is a_____ )two electronB)six electronC)four electronD)one electronE)three electron11)12)The balanced half reaction in which dichromate ion is reduced to chromium metal is a )two electronB)six electronC)twelve electronD)four electronE)three electron12)13)The balanced half reaction in which dichromate ion is reduced to chromium(III) ion is a_____ )three electronB)six electronC)twelve electronD)two electronE)four electron13)214)

3 The balanced half reaction in which sulfate ion is reduced to sulfite ion is a _____ )six electronB)one electronC)four electronD)two electronE)three electron14)15)The electrode at which oxidation occurs is called the _____ .A)cathodeB)oxidizing agentC)reducing agentD)voltaic cellE)anode15)16)The half reaction occurring at the anode in the balanced reaction shown below is (aq) + 24H+ (aq) + 5Fe (s) 3Mn2+ (aq) + 5Fe3+ (aq) + 12H2O (l)A)2 MnO4 (aq) + 12H+ (aq) + 6e 2Mn2+ (aq) + 3H2O (l)B)MnO4 (aq) + 8H+ (aq) + 5e Mn2+ (aq) + 4H2O (l)C)Fe (s) Fe3+ (aq) + 3e D)Fe2+ (aq) Fe3+ (aq) + e E)Fe (s) Fe2+ (aq) + 2e 16)17)In a voltaic cell, electrons flow from the _____ to the )cathode, anodeB)salt bride, anodeC)anode, cathodeD)anode, salt bridgeE)salt bridge, cathode17)18)The reduction half reaction occurring in the standard hydrogen electrode is )

4 2H+ (aq) + 2OH H2O (l)B)O2 (g) + 4H+ (aq) + 4e 2H2O (l)C) 2H+ (aq, 1M) + Cl2 (aq) 2 HCl (aq)D)H2 (g, 1 atm) 2H+ (aq, 1M) + 2e E) 2H+ (aq, 1M) + 2e H2 (g, 1 atm)18)319)1V = )1 J/sB)96485 CC)1 J/CD)1 amp sE)1 C/J19)20)The more _____ the value of E red, the greater the driving force for )exothermicB)extensiveC)endothermicD)neg ativeE)positive20)Table reaction E (V)Cr3+ (aq) + 3e Cr (s) + (aq) + 2e Fe (s) + (aq) + e Fe2+ (s)+ + (aq) + 2e Sn2+ (aq)+ )The standard cell potential (E cell) for the voltaic cell based on the reaction below is _____ + (aq) + 2Fe3+ (aq) 2Fe2+ (aq) + Sn4+ (aq)A)+ )+ )+ ) )+ )22)The standard cell potential (E cell) for the voltaic cell based on the reaction below is _____ (s) + 3Fe3+ (aq) 3Fe2+ (aq) + Cr3+ (aq)A)+ ) )+ )+ )+ )23)The standard cell potential (E cell) for the voltaic cell based on the reaction below is _____ (s) + 3Fe2+ (aq) 3Fe (s) + 2Cr3+ (aq)A) )+ )+ )+ )+ )24)The standard cell potential (E cell) for the voltaic cell based on the reaction below is _____ + (aq) + 2Cr (s) 2Cr3+ (aq) + 3Sn2+ (aq)A)+ ) )+ ) )+ )425)The relationship between the change in Gibbs free energy and the emf of an electrochemical cell isgiven by ) G = nFERTB) G = nFEC) G = EnFD) G = nFEE) G = nRTF25)26)

5 The standard cell potential (E cell) of the reaction below is + V. The value of G for thereaction is _____ (s) + 2H+ (aq) Pb2+ (aq) + H2 (g)A) 24B)+24C) 12D)+12E) 5026)27)The standard cell potential (E cell) for the reaction below is + V. The cell potential for thisreaction is _____ V when [ Zn2+] = M and [Pb2+] = 10 4 + (aq) + Zn (s) Zn2+ (aq) + Pb (s)A) ) ) ) ) )28)The standard cell potential (E cell) for the reaction below is + V. The cell potential for thisreaction is _____ V when the concentration of [Cu2+] = 10 5 M and [Zn2+] = (s) + Cu2+ (aq) Cu (s) + Zn2+ (aq)A) ) ) ) ) )29)The lead containing reactant(s) consumed during recharging of a lead acid battery )PbO2 (s) onlyB)Pb (s) onlyC)PbSO4 (s) onlyD)both PbO2 (s) and PbSO4 (s)E)both Pb (s) and PbO2 (s)29)530)Galvanized iron is iron coated with ) ) ) ) )iron )31)Corrosion of iron is retarded by )the presence of saltsB)low pH conditionsC)high pH conditionsD)both the presence of salts and high pH conditionsE)both the presence of salts and low pH conditions31)32)

6 How many minutes will it take to plate out g of chromium metal from a solution of Cr3+ usinga current of amps in an electrolyte cell _____ ?A) )115C)346D) ) )33)What current (in A) is required to plate out g of nickel from a solution of Ni2+ in hour_____ ?A) ) ) ) ) 10333)34)How many grams of Ca metal are produced by the electrolysis of molten CaBr2 using a current amp for hours _____ ?A) )448C) )112E)22434)35)How many grams of CuS are obtained by passing a current of 12 A through a solution of CuSO4for 15 minutes _____ ?A) ) )14D) ) )36)How many seconds are required to produce g of silver metal by the electrolysis of a AgNO3solution using a current of 30 amps _____ ?

7 A) 10 5B)60C) 103D)30E) 10436)37)How many grams of copper will be plated out by a current of A applied for 25 minutes to M solution of copper(II) sulfate _____ ?A) ) ) ) ) 10 237)6 Answer KeyTestname: Chapter 20 Practice QUESTIONS1)B2)D3)C4)B5)D6)C7)C8)C9)D10)A 11)A12)C13)B14)D15)E16)C17)C18)E19)C20)E 21)A22)C23)E24)C25)D26)A27)E28)A29)C30)A 31)C32)E33)C34)E35)A36)D37)D7