Deck 14: Electrochemistry

Question 1

Given: PH₃(g) $\rightarrow$ P₄(s),basic solution. How many electrons appear in the balanced half-reaction?

A)12
B)9
C)6
D)8
E)3

Answer 1

12

Question 2

The standard potential of the Cu²⁺/Cu electrode is +0.34 V and the standard potential of the cell Ag(s)|AgCl(s)|Cl^-(aq)m Cu²⁺(aq)|Cu(s)
Is +0.12 V.What is the standard potential of the AgCl/Ag,Cl^- electrode?

A)-0.46 V
B)-0.22 V
C)+0.24 V
D)+0.46 V
E)+0.22 V

Answer 2

+0.22 V

Question 3

When equilibrium is reached in an electrochemical cell,the voltage reaches its maximum value.

Answer 3

False

Question 4

A cell that uses bromine to oxidize chloride ion under standard conditions at 298 K has a positive potential.True or false?

Question 5

When the Ag(s)|AgCl(s)|Cl^-(aq)electrode acts as a cathode,the reaction is

A)Ag⁺(aq)+ e^- $\rightarrow$ Ag(s).
B)Ag(s)+ Cl^-(aq) $\rightarrow$ AgCl(s)+ e^-
C)Ag(s) $\rightarrow$ Ag⁺(aq)+ e^-
D)2AgCl(s)+ 2e^- $\rightarrow$ 2Ag⁺(aq)+ Cl₂(g).
E)AgCl(s)+ e^- $\rightarrow$ Ag(s)+ Cl^-(aq).

Question 6

In the determination of iron in vitamins,Fe²⁺ is titrated with permanganate,MnO₄^-,in acidic solution.The products of the reaction are Fe³⁺ and Mn²⁺.In the balanced equation,the number of electrons transferred is

A)5
B)1
C)10
D)7

Question 7

Given: N₂H₅⁺(aq) $\rightarrow$ N₂(g). How many electrons appear in the balanced half-reaction?

A)6
B)2
C)1
D)4
E)5

Question 8

The standard potential of the Cu²⁺/Cu electrode is +0.34 V and the standard potential of the cell Pb(s)|Pb²⁺(aq)m Cu²⁺(aq)|Cu(s)
Is +0.47 V.What is the standard potential of the Pb²⁺/Pb electrode?

A)-0.26 V
B)+0.81 V
C)-0.81V
D)-0.13 V
E)+0.13 V

Question 9

If the standard potentials for the couples Cu²⁺/Cu,Ag⁺/Ag,and Fe²⁺/Fe are +0.34,+0.80,and -0.44 V,respectively,which is the strongest reducing agent?

A)Fe
B)Ag
C)Ag⁺
D)Cu
E)Fe²⁺

Question 10

What is the proper cell diagram for the reaction 2AgCl(s)+ H₂(g) $\rightarrow$ 2Ag(s)+ 2H⁺(aq)+ 2Cl^-(aq)

A)Pt|Cl^-(aq)|H⁺(aq)m H₂(g)|AgCl(s)|Ag(s)
B)Pt|H₂(g)|H⁺(aq)m Cl^-(aq)|AgCl(s)|Ag(s)
C)Ag(s)|AgCl(s)|Cl^-(aq)m H⁺(aq)|H₂(g)|Pt
D)Pt|H₂(g)|H⁺(aq)m Cl^-(aq)|Ag(s)|Pt
E)Ag(s)|AgCl(s)|H⁺(aq)m Cl^-(aq)|H₂(g)|Pt

Question 11

Given: S₂O₄^2-(aq) $\rightarrow$ SO₃^2-(aq),basic solution. How many electrons appear in the balanced half-reaction?

A)3
B)6
C)1
D)4
E)2

Question 12

A cell that uses bromine to oxidize hydrogen to H⁺ under standard conditions at 298 K has a negative potential?

Question 13

When a sample of an unknown metal is dropped into 1 M H⁺(aq)under standard conditions,bubbles are observed.The unknown metal could be silver.

Question 14

Given: Zn(s)+ OH^-(aq)+ H₂O(l)+ NO₃^-(aq) $\rightarrow$ Zn(OH)₄^2-(aq)+ NH₃(g) If the coefficient of NO₃^- in the balanced equation is 1,how many electrons are transferred in the reaction?

A)10
B)6
C)2
D)4
E)8

Question 15

In a working electrochemical cell (+ cell voltage),the cations in the salt bridge move toward the cathode.

Question 16

How many electrons appear in the balanced half reaction: NO₃^-(aq)F $\rightarrow$ NO(g),in acidic solution?

A)2
B)3
C)4
D)6
E)8

Question 17

Given: Cr(OH)₃(s) $\rightarrow$ CrO₄^2-(aq),basic solution. How many electrons appear in the balanced half-reaction?

A)3
B)6
C)5
D)7
E)4

Question 18

In a working electrochemical cell (+ cell voltage),the electrons flow from the anode through the external circuit to the cathode.

Question 19

If the standard potentials for the couples Fe³⁺/Fe²⁺,MnO₄2^-0,H⁺/Mn²⁺,H₂O,Zn²⁺/Zn,V³⁺/V²⁺,and Br₂/Br^- are +0.77,+1.51,-0.76,-0.26,and +1.09 V,respectively,which is the strongest oxidizing agent?

A)Zn²⁺
B)Fe³⁺
C)Mn²⁺
D)Br₂
E)MnO₄^-

Question 20

For the cell diagram Pt|H₂(g),H⁺(aq)m Cu²⁺(aq)|Cu(s)
Which reaction occurs at the anode?

A)Cu(s) $\rightarrow$ Cu²⁺(aq)+ 2e^-
B)2H⁺(aq)+ 2e^- $\rightarrow$ H₂(g)
C)2H⁺(aq)+ Cu(s) $\rightarrow$ H₂(g)+ Cu²⁺(aq)
D)Cu²⁺(aq)+ 2e^- $\rightarrow$ Cu(s)
E)H₂(g) $\rightarrow$ 2H⁺(aq)+ 2e^-

Question 21

The standard potential of the cell Pb(s)|PbSO₄(s)|SO₄^2-(aq)m Pb²⁺(aq)|Pb(s)
Is +0.23 V at 25 ^$\circ$ C.Calculate the equilibrium constant for the reaction of 1 M Pb²⁺(aq)with 1M SO₄^2-(aq).

A)3.7 * 10¹⁶
B)8.0 * 10¹⁷
C)6.0 * 10⁷
D)1.7 * 10^-8
E)7.7 * 10³

Question 22

Of the following five ions or molecules,which is the strongest reducing agent?

A)Fe²⁺
B)Cr²⁺
C)F^-
D)H₂
E)Co²⁺

Question 23

Which of the following occurs when HNO₃(aq),Cu(s),and Pt(s)are mixed under standard conditions?

A)Pt(s)dissolves.
B)No reaction takes place.
C)Cu(s)dissolves.
D)Pt(s)dissolves and H₂(g)is formed.
E)Cu(s)dissolves and H₂(g)is formed.

Question 24

Which species will reduce Br₂ but not V³⁺?

A)Ce
B)Zn
C)Cu
D)Cr²⁺
E)Al

Question 25

Consider the following cell at standard conditions: Zn(s)|Zn²⁺(aq)m Fe²⁺(aq)|Fe(s)
Calculate the value of $\Delta$ G_r ^$\circ$ for the reaction that occurs when current is drawn from this cell.

A)-62 kJ.mol^-1
B)-230 kJ.mol^-1
C)+62 kJ.mol^-1
D)+230 kJ.mol^-1
E)-31 kJ.mol^-1

Question 26

The standard potential of the cell Ag(s)|AgCl(s)m Cl^-(aq)|Cu²⁺(aq)|Cu(s)
Is +0.12 V at 25 ^$\circ$ C.If the standard potential of the Cu²⁺/Cu couple is +0.34 V,calculate the standard potential of the AgCl/Ag,Cl^-couple.

A)-0.12 V
B)-0.46 V
C)+0.46 V
D)-0.22 V
E)+0.22 V

Question 27

Consider the following reaction: 2Cu⁺(aq) $\rightarrow$ Cu(s)+ Cu²⁺(aq)
If the standard potentials of Cu²⁺ and Cu⁺ are +0.34 and +0.52 V,respectively,calculate the value of E ^$\circ$ for the given reaction.

A)+0.86 V
B)+0.70 V
C)+0.18 V
D)-0.18 V
E)-0.70 V

Question 28

Calculate E ^$\circ$ for the following cell. Zn(s)|Zn²⁺(aq)m Cl^-(aq)|AgCl(s)|Ag(s)

A)+0.54 V
B)+1.20 V
C)-1.20 V
D)+0.98 V
E)-0.54 V

Question 29

If the standard free energy change for combustion of 1 mole of CH₄(g)is -818 kJ.mol^-1,calculate the standard voltage that could be obtained from a fuel cell using this reaction.

A)-1.06 V
B)+0.53 V
C)+4.24 V
D)+8.48 V
E)+1.06 V

Question 30

Which of the following is the strongest oxidizing agent?

A)O₃
B)MnO₄^-
C)Cr₂O₇^2-
D)Cl₂

Question 31

If the standard potential for Cu²⁺(aq)/Cu⁺(aq)is 0.15 V and the standard potential for Cu²⁺(aq)/Cu(s)is 0.34 V,calculate the standard potential for Cu⁺(aq)+ e^- $\rightarrow$ Cu(s).

A)+0.32 V
B)+0.64 V
C)+0.53 V
D)+0.83 V
E)+0.49 V

Question 32

If the standard potential for Ti³⁺(aq)/Ti²⁺(aq)is -0.37 V and the standard potential for Ti²⁺(aq)/Ti(s)is -1.63 V,calculate the standard potential for Ti³⁺(aq)+ 3e^- $\rightarrow$ Ti(s).

A)-1.19 V
B)-0.40 V
C)-2.00 V
D)-1.26 V
E)-1.21 V

Question 33

Which species will reduce Ag⁺ but not Fe²⁺?

A)Pt
B)Au
C)V
D)Cr
E)H₂

Question 34

Which species will oxidize Cr²⁺ but not Mn²⁺?

A)Pb⁴⁺
B)O₃ in acidic medium
C)Zn²⁺
D)Fe²⁺
E)V³⁺

Question 35

Consider the reaction: 2Ag⁺(aq)+ Cu(s) $\rightarrow$ Cu²⁺(aq)+ 2Ag(s)
If the standard potentials of Ag⁺ and Cu²⁺ are +0.80 V and +0.34 V,respectively,calculate the value of E ^$\circ$ for the given reaction.

A)+1.48 V
B)-1.26 V
C)-0.46 V
D)+1.26 V
E)+0.46 V

Question 36

Which of the following occurs when HCl(aq),Cu(s),and Fe(s)are mixed under standard conditions?

A)O₂(g)is formed.
B)Cu(s)dissolves.
C)Cl₂(g)is formed.
D)No reaction takes place.
E)Fe(s)dissolves.

Question 37

Which metal will dissolve in hydrochloric acid?

A)All the metals listed will dissolve.
B)Fe
C)Ag
D)Pt
E)Au

Question 38

Given: Ag⁺(aq)+ e^- $\rightarrow$ Ag(s)
E° = 0.80 V
Fe³⁺(aq)+ e^- $\rightarrow$ Fe²⁺(aq)
E ^$\circ$ = 0.77 V
Cu²⁺(aq)+ 2e^- $\rightarrow$ Cu(s)
E ^$\circ$ = 0.34 V
Which is the strongest reducing agent?

A)Ag
B)Cu²⁺
C)Cu
D)Ag⁺
E)Fe²⁺

Question 39

If the standard potential for Tl³⁺(aq)/Tl⁺(aq)is 1.21 V and the standard potential for Tl⁺(aq)/Tl(s)is -0.34 V,calculate the standard potential for Tl³⁺(aq)+ 3e^- $\rightarrow$ Tl(s).

A)0.69 V
B)0.87 V
C)1.55 V
D)0.09 V
E)0.29 V

Question 40

Which pair of metals will dissolve in nitric acid?

A)Pt,Ag
B)Pt,Au
C)Ag,Fe
D)Ag,Au
E)Pt,Fe

Question 41

Consider the following cell:
Pt|Fe²⁺(aq,0.50 M),Fe³⁺(aq,0.30 M)m Fe³⁺(aq,0.035 M),Fe²⁺(aq,0.010)|Pt
The standard potential for the Fe³⁺/Fe²⁺ couple is +0.77 V.Calculate the cell voltage at 25 ^$\circ$ C.

Question 42

What is the value of E for the following reaction?
2H⁺(aq,1.00 M)+ 2e^-F $\rightarrow$ H₂(g,1.00 atm)

Question 43

The standard potential of the cell Pb(s)|PbSO₄(s)|SO₄^2-(aq)m Pb²⁺(aq)|Pb(s)
Is +0.23 V at 25 ^$\circ$ C.Calculate the K_sp of PbSO₄.

A)1.3 * 10^-18
B)1.7 * 10^-8
C)1.3 * 10^-4
D)2.7 * 10^-17
E)6.0 * 10⁷

Question 44

The standard voltage of the cell Ag(s)|AgBr(s)|Br^-(aq)m Ag⁺(aq)|Ag(s)
Is +0.73 V at 25 ^$\circ$ C.Calculate the K_sp for AgBr.

A)3.9 * 10^-29
B)2.2 * 10¹²
C)2.0 * 10^-15
D)5.1 * 10¹⁴
E)4.6 *10^-13

Question 45

The equilibrium constant for the reaction 2Hg(l)+ 2Cl^-(aq)+ Ni²⁺(aq) $\rightarrow$ Ni(s)+ Hg₂Cl₂(s)
Is 5.6 * 10^-20 at 25 ^$\circ$ C.Calculate the value of E ^$\circ$ for a cell utilizing this reaction.

A)+0.57 V
B)-0.25 V
C)+1.14 V
D)-1.14 V
E)-0.57 V

Question 46

Consider the following cell: Ag(s)|Ag⁺(aq,0.100 M)mAg⁺(aq,0.100 M)|Ag(s)
What is the voltage of this cell?

A)0
B)+0.0592 V
C)+0.0296 V
D)+0.80 V

Question 47

If E ^$\circ$ for the following cell is 0.36 V at 25 ^$\circ$ C Pb(s)|PbSO₄(s)|SO₄^2-(aq,0.60 M)m H⁺(aq,0.70 M)|H₂(g,192.5 kPa)|Pt
How is the Nernst equation for the cell properly expressed at this temperature?

A)E = 0.36 - 0.01285ln[1.90/{(0.70)²(0.60)}]
B)E = 0.36 - 0.02569ln[192.5/{(0.70)²(0.60)}]
C)E = 0.36 + 0.01285ln[192.5/{(0.70)²(0.60)}]
D)E = 0.36 + 0.01285ln[1.90/{(0.70)²(0.60)}]
E)E = 0.36 - 0.01285ln[1.90/{(0.70)(0.60)}]

Question 48

Use the following diagram of a cell to answer questions

-In the cell shown above,A is a standard Zn²⁺/Zn electrode connected to a standard hydrogen electrode (SHE).If the voltmeter reading is -0.76 V,what is the equation for the cell reaction?

A)Zn²⁺(aq)+ H₂(g) $\rightarrow$ Zn(s)+ 2H⁺(aq)
B)Zn(s)+ 2H⁺(aq) $\rightarrow$ Zn²⁺(aq)+ H₂(g)

Question 49

Use the following to answer questions
The galvanic cell shown above uses the half-cells Pb²⁺/Pb and Zn²⁺/Zn,and a salt bridge containing KCl(aq).The voltmeter gives a positive voltage reading.The electrode B could be inert platinum metal or lead.

Question 50

The standard voltage of the cell Ag(s)|AgBr(s)|Br^-(aq)m Ag⁺(aq)|Ag(s)
Is +0.73 V at 25 ^$\circ$ C.Calculate the equilibrium constant for the cell reaction.

A)5.1 * 10¹⁴
B)2.0 * 10^-15
C)2.2 * 10¹²
D)4.6 * 10^-13
E)3.9 * 10^-29

Question 51

The standard voltage of the cell Pt|H₂(g)|H⁺(aq)m Cl^-(aq)|AgCl(s)|Ag(s)
Is +0.22 V at 25 ^$\circ$ C.Calculate the equilibrium constant for the reaction below.
2AgCl(s)+ H₂(g) $\rightarrow$ 2Ag(s)+ 2H⁺(aq)+ 2Cl^-(aq)

A)3.7
B)7.4
C)5.2 * 10³
D)1.7 * 10³
E)2.7 * 10⁷

Question 52

Consider the following cell: Zn(s)|Zn²⁺(aq,0.100 M)m Cl^-(aq,? M)|Cl₂(g,0.500 atm)|Pt
For this cell,E ^$\circ$ = 2.12 V and E = 2.27 V at 25 ^$\circ$ C.Calculate the Cl^-(aq)concentration in the cathode compartment.

A)1.2 * 10^-1 M
B)4.3 *10^-5 M
C)2.9 *10^-3 M
D)1.5 * 10^-3 M
E)6.5 * 10^-3 M

Question 53

Calculate E for the half-reaction below. 2H⁺(aq,1.00 * 10^-5 M)+ 2^- $\rightarrow$ H₂(g,1.00 atm)

A)0 V
B)+0.592 V
C)-0.592 V
D)-0.296 V
E)+0.296 V

Question 54

Use the following to answer questions

-The galvanic cell shown above uses the half-cells Pb²⁺/Pb and Zn²⁺/Zn,and a salt bridge containing KCl(aq).The voltmeter gives a positive voltage reading.Identify A and write the half-reaction that occurs in that compartment.Does the size of the electrode A increase or decrease during operation of the cell? What is the voltmeter reading?

Question 55

Use the following diagram of a cell to answer questions

-In the cell shown above,A is a standard Zn²⁺/Zn electrode connected to a standard hydrogen electrode (SHE).If the voltmeter reading is -0.76 V,which half-reaction occurs in the left-hand cell compartment?

A)Zn²⁺(aq)+ 2e^- $\rightarrow$ Zn(s)
B)Zn(s) $\rightarrow$ Zn²⁺(aq)+ 2e^-

Question 56

If E ^$\circ$ for the disproportionation of Cu⁺(aq)to Cu²⁺(aq)and Cu(s)is +0.18 V at 25 ^$\circ$ C,calculate the equilibrium constant for the reaction.

A)1.2 * 10⁶
B)3.9 * 10⁷⁴
C)2.5 * 10¹⁴
D)35.7
E)3.3 * 10¹²

Question 57

Consider the following cell:
Zn(s)|Zn²⁺(aq,0.200 M)m H⁺(aq,?)|H₂(g,1.00 atm)|Pt
If E = +0.66 V and E ^$\circ$ = +0.76 V at 25 ^$\circ$ C,calculate the concentration of H⁺ in the cathode cell compartment.

A)2.1 * 10^-2 M
B)4.0 * 10^-1 M
C)8.4 * 10 ^-5 M
D)9.2 *10 ^-3 M
E)4.0 * 10 ^-3 M

Question 58

Use the following to answer questions
The galvanic cell shown above uses the half-cells Pb²⁺/Pb and Zn²⁺/Zn,and a salt bridge containing KCl(aq).The voltmeter gives a positive voltage reading.The electrode B could be inert platinum metal or zinc.

Question 59

Use the following to answer questions

-The galvanic cell shown above uses the half-cells Mg²⁺/Mg and Zn²⁺/Zn,and a salt bridge containing KCl(aq).The voltmeter gives a positive voltage reading.Identify A and write the half-reaction that occurs in that compartment.Does the size of the electrode A increase or decrease during operation of the cell? What is the voltmeter reading?

Question 60

Consider the following cell: Pt|H₂(g,1 atm)|H⁺(aq,? M)m Ag⁺(aq,1.0 M)|Ag(s)
If the voltage of this cell is 1.04 V at 25 ^$\circ$ C and the standard potential of the Ag⁺/Ag couple is +0.80 V,calculate the hydrogen ion concentration in the anode compartment.

A)4.6 *10^-10 M
B)8.8 * 10^-5 M
C)9.4 * 10^-3 M
D)1.0 M
E)3.7 * 10^-8 M

Question 61

Sodium is produced by electrolysis of molten sodium chloride.What are the products at the anode and cathode,respectively?

A)Na(l)and O₂(g)
B)Cl^-(aq)and Na₂O(l)
C)Cl₂(g)and Na₂O(l)
D)O₂(g)and Na(l)
E)Cl₂(g)and Na(l)

Question 62

The half-reaction that occurs at cathode when 1 M AgNO₃(aq)is electrolyzed is __________________.

Question 63

What current is required to produce 91.6 g of chromium meta from chromium(VI)oxide in 12.4 hours?

Question 64

Galvanized iron is protected from corrosion because zinc reduces any Fe²⁺ formed.

Question 65

The products of the electrolysis of CuSO₄(aq)are

A)H₂(g)and H₂SO₃(aq).
B)H₂SO₃(aq)and O₂(g).
C)Cu(s)and H₂SO₃(aq).
D)Cu(s)and O₂(g).
E)H₂(g)and O₂(g).

Question 66

If 8686 C of charge is passed through molten magnesium chloride,calculate the number of moles of Mg(l)produced.

A)0.0225 mol
B)0.0450 mol
C)2.00 mol
D)0.0110 mol
E)0.0900 mol

Question 67

When KI(aq)is electrolyzed at a concentration of 1 M,the product at the anode is I₂.

Question 68

How many moles of Cl₂(g)are produced by the electrolysis of concentrated sodium chloride if 2.00 A are passed through the solution for 4.00 hours? The equation for this process,the "chloralkali" process,is 2NaCl(aq)+ 2H₂O(l) $\rightarrow$ 2NaOH(aq)+ H₂(g)+ Cl₂(g)

A)0.0745 mol
B)0.149 mol
C)0.447 mol
D)0.00248 mol
E)0.298 mol

Question 69

For the reduction of Cu²⁺ by Zn, ^$\circ$ G^o = -212 kJ/mol and E^o = +1.10 V.If the coefficients in the chemical equation for this reaction are multiplied by 2, ^$\circ$ G^o = -424 kJ/mol.This means E^o = +2.20 V.

Question 70

How long will it take to deposit 0.00235 moles of gold by electrolysis of KAuCl₄(aq)using a current of 0.214 amperes?

A)17.7 min
B)26.5 min
C)70.7 min
D)106 min
E)53.0 min

Question 71

Of the following metals,which metal would be suitable to provide an iron bridge with cathodic protection from corrosion?

A)Ni
B)Cu
C)Pb
D)Sn
E)None of the metals listed is suitable.

Question 72

Use the following diagram of a cell to answer questions

-In the cell shown above,A is a standard Zn²⁺/Zn electrode connected to a standard hydrogen electrode (SHE).If the voltmeter reading is -0.76 V,which electrode is negative?

Question 73

In order to convert hydrazine,N₂H₄,to nitric acid,

A)an oxidizing agent is required.
B)a reducing agent is required.

Question 74

How many moles of O₂(g)are produced by electrolysis of Na₂SO₄(aq)if 0.120 A is passed through the solution for 65.0 min?

A)0.001 21 mol
B)0.000 080 8 mol
C)0.002 42 mol
D)0.004 85 mol
E)0.000 020 2 mol

Question 75

In the Daniell cell,the anode is zinc metal and the cathode is copper metal.When the cell operates,the anode gets smaller and the cathode gets larger.

Question 76

Use the following diagram of a cell to answer questions
In the cell shown above,A is a standard Ag⁺/Ag electrode connected to a standard hydrogen electrode (SHE).If the voltmeter reading is +0.80 V,which electrode is negative?

Question 77

Use the following diagram of a cell to answer questions

-Using the cell shown above,A is a standard Ag⁺/Ag electrode connected to a standard hydrogen electrode (SHE).When the voltmeter reading is -0.80 V,which half-reaction occurs in the left-hand cell compartment?

A)Ag(s) $\rightarrow$ Ag⁺(aq)+ e^-
B)Ag⁺(aq)+ e^- $\rightarrow$ Ag(s)

Question 78

How many seconds are required to produce 4.99 mg of chromium metal from an acidic solution of potassium dichromate,using a current of 0.234 A?

Question 79

Use the following diagram of a cell to answer questions

-In the cell shown above,A is a standard Ag⁺/Ag electrode connected to a standard hydrogen electrode (SHE).If the voltmeter reading is +0.80 V,what is the equation for the cell reaction?

A)Ag(s)+ H⁺(aq) $\rightarrow$ Ag⁺(aq)+ ½H₂(g)
B)Ag⁺(aq)+ ½H₂(g) $\rightarrow$ Ag(s)+ H⁺(aq)

Question 80

When a lead-acid battery discharges,sulfuric acid is produced.