Ch.18 - ElectrochemistryWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Galvanic (Voltaic Cells) & Electrolytic Cells

Concept #1: Galvanic versus Electrolytic Cells

Concept #2: An electrolytic cell presents an electrochemical cell that is nonspontaneous. 

Example #1: A certain electrochemical cell involves a five electron change and has a value of Keq = 3.0 x 1016 at 298 K. The value of ΔHo for the reaction is -68.3 kJ/mol. Calculate the values of ΔGo, ΔEo, for a standard electrochemical cell constructed based on this reaction and also ΔSo for the reaction.

Practice: Given the following standard reduction potentials,

Hg22+(aq)  +  2 e    2 Hg (?)                                                          E° = +0.789 V

 

Hg2Cl2(s)  +  2 e    2 Hg (?)  +  2 Cl-(aq)                                        E° = +0.271 V

determine Ksp for Hg2Cl2(s) at 25 °C.

Example #2: The cell notation for a redox reaction is given as the following at (T = 298 K):

Zn (s) Ι Zn2+ (aq, 0.37 M) ΙΙ Ni2+ (aq, 0.059 M) Ι Ni (s)

a)  Write the balanced half-reactions occurring at the anode and the cathode.

b)  Write out the complete balanced redox reaction.

c)  Determine the Eo cell.

d)  Calculate the maximum electrical work that can be produced by this cell.

e)  Calculate the reactant quotient, Q, for this cell and the cell potential under non-standard conditions.

 

Example #3: Answer each of the following questions based on the following half reactions:

HALF REACTIONS                                Eo (V)

Cl2 (g)  +  2 e            2 Cl (aq)          + 1.36

l2 (g)  +  2 e              2 l (aq)             + 0.535

Pb2+ (aq)   +  2 e      Pb (s)                  - 0.126

V2+ (aq)  +  2 e         V (s)                    - 1.18

a)  Which is the strongest oxidizing agent?

b)  Which is the strongest reducing agent?

c)  Will I (aq) reduce Cl2 (g) to Cl (g)?

Example #4: Electric current, or flow of electrons is measured in Amperes (A). One Ampere is the delivery of one coulomb (C) of charge per second. What mass of Zinc (in g) is oxidized (to Zn2+) by a dry cell battery that supplies 125 mA of current for two hours (recall that Faraday's constant is the charge in coulombs on a mole of electrons)? 

Example #5: Consider the combustion of formaldehyde CH2O and the data below for the following five questions.

            I. CH2O (g)  + O(g)   →   CO(g)  +  H2O (l)

            II. 4H+  +  4 e -  +  O(g)   →   2 H2O (l)                              ΔE° = 1.23V

Which compound is reduced in reaction I?

{C}a.    {C}CH2O

{C}b.    {C}H2O

{C}c.    {C}O2

{C}d.    {C}CO2

{C}e.    {C}None of these

What is the change in oxidation number of the carbon in reaction I?

{C}a.    {C}-4

{C}b.    {C}-1

{C}c.    {C}0

{C}d.    {C}1

{C}e.    {C}4

Example #6: The purpose of a galvanic cell is to:

a. Transduce chemical energy to electrical energy.

b. Purify solids.

c. Allow for oxidation without reduction.

d. To consume electricity. 

Example #7: During the process for electrolysis of water a current is passed through water and produces hydrogen gas and oxygen gas. Which of the following statements is true?

a. O2 gas is produced at the anode.

b. H2 gas is produced at the cathode.

c. In the reaction, H2 moles are twice the O2 moles.

d. All of the following are correct. 

Example #8: Which statement is false?

a. Reduction occurs at the cathode.

b. A reducing agent will lose electrons.

c. Cations migrate to the cathode in both electrolytic and electrochemical cells.

d. Li (s) is the strongest oxidizing agent; F2 is the strongest reducing agent. 

Example #9: Which of the following reactions may occur at the anode? 

a. Ga3+ (aq)  +  3 e   →   Ga (s) 

b. Cu2+ (aq)  +  2 e   →   Cu (s) 

c. 2 Cl (aq)    →   Cl2 (g)  +  3 e 

d. Co (s)  +  e   →   Co+ (aq) 

Example #10: Define a salt bridge.

A) A pathway, composed of salt water, that ions pass through.

B) A pathway in which no ions flow.

C) A pathway between the cathode and anode in which ions are reduced.

D) A pathway between the cathode and anode in which ions are oxidized.

E) A pathway by which counterions can flow between the half-cells without the solutions in the half-cell totally mixing.

Example #11: What statement is NOT true about standard electrode potentials?

A) E°cell is positive for spontaneous reactions.

B) Electrons will flow from more negative electrode to more positive electrode.

C) The electrode potential of the standard hydrogen electrode is exactly zero.

D) E°cell is the difference in voltage between the anode and the cathode.

E) The electrode in any half-cell with a greater tendency to undergo reduction is positively charged relative to the standard hydrogen electrode and therefore has a positive E°.

Example #12: Use the standard reduction potentials below to determine which element or ion is the best reducing agent.

Pd2+ (aq)  +  2 e  →  Pd (s)               Eo = + 0.90 V

2 H+ (aq)  +  2 e  →  H2 (g)               Eo =    0.00 V

Mn2+ (aq)  +  2 e  →  Mn (s)               Eo = - 1.18 V

a) Pd (s)              b) H+ (aq)              c) Mn2+ (aq)              d) H2 (g)

Example #13: Consider an electrochemical cell where the following reaction takes place:

Na2O (aq) + Ba (s)  →  2 Na (s) + BaO (aq)

What is the cell notation for this cell? 

 

What is the ratio of oxidizing agent to reducing agent? 

Additional Problems
Draw an electrolytic cell in which Mn2+ is reduced to Mn and Sn is oxidized to Sn2+. Label the anode and cathode, indicate the direction of electron flow, and write an equation for the half-reaction occurring at each electrode. What minimum voltage is necessary to drive the reaction?
Which of the following general statements (in a‐c) are FALSE? a) Oxidation occurs at the anode of a voltaic cell b) The potential of a cell depends on its temperature c) A functioning voltaic cell has a negative emf d) Both statements a and b are false e) All statements a, b, and c are false
Complete the following statement: In a galvanic cell, the anions migrate toward the (anode/cathode) and the electrons flow through an external circuit from the (anode/cathode) to the (anode/cathode).
Consider the molecular view of an electrochemical cell involving the overall reaction: Zn(s) + Ni2+(aq) → Zn2+(aq) + Ni(s) Draw a similar sketch of the cell after it has generated a substantial amount of electrical current.
What is the balanced half‐reaction that occurs at the anode in the unbalanced overall cell reaction of a voltaic cell: 3 MnO4– + 5 Fe (s) → 3 Mn2+ + 5 Fe3+ a) MnO 4- (aq) + 8H (aq) + 5e - → Mn2+ (aq) + 4H 2 O(l)  b) 2MnO 4- (aq) +12H+ (aq) + 6e - → 2Mn2+ (aq) + 3H 2 O(l) c) Fe(s) → Fe3+ (aq) + 3e - d) Fe(s) → Fe2+ (aq) + 2e - e) Fe2+ (s) → Fe3+ (aq) + e -    
Identify the location of oxidation in an electrochemical cell. A) the salt bridge B) the socket C) the electrode D) the anode E) the cathode
The purpose of a galvanic cell is to: a. Transduce chemical energy to electrical energy. b. Purify solids. c. Allow for oxidation without reduction. d. To consume electricity. 
Which statement is false? a. Reduction occurs at the cathode. b. A reducing agent will lose electrons. c. Cations migrate to the cathode in both electrolytic and electrochemical cells. d. Li (s) is the strongest oxidizing agent; F2 is the strongest reducing agent. 
Define a salt bridge.   A) A pathway, composed of salt water, that ions pass through. B) A pathway in which no ions flow. C) A pathway between the cathode and anode in which ions are reduced. D) A pathway between the cathode and anode in which ions are oxidized. E) A pathway by which counterions can flow between the half-cells without the solutions in the half-cell totally mixing.
What statement is NOT true about standard electrode potentials? A) E°cell is positive for spontaneous reactions. B) Electrons will flow from more negative electrode to more positive electrode. C) The electrode potential of the standard hydrogen electrode is exactly zero. D) E°cell is the difference in voltage between the anode and the cathode. E) The electrode in any half-cell with a greater tendency to undergo reduction is positively charged relative to the standard hydrogen electrode and therefore has a positive E°.
What is the name given to the experimental apparatus for generating electricity through the use of a spontaneous reaction? A) electrolytic cell B) galvanic cell C) fuel cell D) cathodic cell E) anodic cell
Choose the correct statement. A) The cathode is the electrode where the oxidation takes place. B) The cathode is the electrode where the reduction takes place. C) Both oxidation and reduction may take place at the cathode, depending on the cell. D) The cathode is always positive. E) The anode is always negative.
When designing a voltaic cell with the following cell notation:                         Li(s) | Li+(aq) ‖ Zn2+(aq) | Zn(s) That uses a salt bridge made of NaCl, what answer describes what is occurring at the anode? A.  Lithium is being oxidized and Cl − joins the solution B.  Lithium is being reduced and Cl − joins the solution C.  Zinc is being oxidized and Cl− joins the solution D.  Zinc is being oxidized and Na+ joins the solution E.  Lithium is being oxidized and Na+ joins the solution
Sketch a voltaic cell for each redox reaction. Label the anode and cathode and indicate the half-reaction that occurs at each electrode and the species present in each solution. Also indicate the direction of electron flow. a. Ni2+(aq) + Mg(s) → Ni(s) + Mg2+(aq)  
Sketch a voltaic cell for each redox reaction. Label the anode and cathode and indicate the half-reaction that occurs at each electrode and the species present in each solution. Also indicate the direction of electron flow. b. 2 H+(aq) + Fe(s) → H 2(g) + Fe2+(aq)  
Consider the voltaic cell: a. Determine the direction of electron flow and label the anode and the cathode. b. Write a balanced equation for the overall reaction and calculate E°cell. c. Label each electrode as negative or positive.  d. Indicate the direction of anion and cation flow in the salt bridge.
Design a voltaic cell from the following half-reactions: Cr 2O 7(aq) + 14 H +(aq) + 6 e − → 2 Cr 3+ (aq) + 7 H 2O(l)              E  o = 1.33 O 2(g) + 4 H +(aq) + 4 e − → H 2O(l)                                                 E     o = 1.23 In the overall reaction, how many H + ions would be shown and which side would they be on? A. 18 on the left B. 16 on the left C. 10 on the left D. 10 on the right E. 12 on the right  
What is the name given to the experimental apparatus for generating electricity through the use of a spontaneous reaction? a) electrolytic cell b) voltaic cell c) fuel cell d) standard cell e) anode cell
Make a sketch of a concentration cell employing two Zn/Zn2+ half-cells. The concentration of Zn2+ in one of the half-cells is 2.0 M and the concentration in the other half-cell is 1.0 X 10–3 M. Label the anode and the cathode and indicate the half-reaction occurring at each electrode . Also indicate the direction of electron flow.
Consider the concentration cell: a. Label the anode and cathode. b. Indicate the direction of electron flow. c. Indicate what happens to the concentration of Pb2+ in each half-cell.
The diagram below represents a molecular view of a process occurring at an electrode in a voltaic cell. Why are the atoms in the electrode represented by larger spheres than the ions in the solution?
Indicate whether each statement is true or false:Electrons flow spontaneously from anode to cathode in a voltaic cell.
Indicate whether each statement is true or false:A galvanic cell is another name for a voltaic cell.
Do all voltaic cells produce a positive cell potential?
A Cu-Zn voltaic cell based on the reaction in the equation given below. Zn( s ) + Cu2 + ( aq )  →  Zn2 + ( aq ) + Cu( s )Which metal is oxidized in this voltaic cell?
A spontaneous oxidation-reduction reaction involving zinc and copper.Why does the intensity of the blue solution color lessen as the reaction proceeds?
A voltaic cell is constructed that uses the following half-cell reactions: l Cu+ (aq) + e-  →  Cu(s)I2 (s) + 2e-  →  2I- (aq) .The cell is operated at 298 K with [Cu+ ] = 0.26 M and [I- ] = 3.6 M .Which electrode is the anode of the cell?
Indicate whether each of the following statements is true or false.If you double the concentrations of reagents in a voltaic cell, you will double the voltage obtainable.
Consider the following voltaic cell. Which electrode is the cathode?
In electrochemistry, spontaneous redox reactions are used for what purpose?
What reaction (oxidation or reduction) occurs at the anode of a voltaic cell?
What reaction (oxidation or reduction) occurs at the cathode of a voltaic cell?
What is a concentration electrochemical cell?
A voltaic cell that uses a salt bridge to complete the electrical circuit.How is electrical balance maintained in the left beaker as Zn2+ ions are formed at the anode?
Which electrode of a voltaic cell, the cathode or the anode, corresponds to the higher potential energy for the electrons?
A voltaic cell is constructed with two Zn2 + - Zn electrodes. The two cell compartments have [Zn2 + ] = 1.8 M and [Zn2 + ] = 1.60×10−2 M , respectively.Which electrode is the anode of the cell?
The diagram below represents a molecular view of a process occurring at an electrode in a voltaic cell. Does the process represent oxidation or reduction?
The diagram below represents a molecular view of a process occurring at an electrode in a voltaic cell. Is the electrode the anode or cathode?
Are electrolysis reactions thermodynamically spontaneous?
Explain the purpose of a salt bridge in an electrochemical cell.
Consider the electrolytic cell:a. Label the anode and the cathode and indicate the halfreactions occurring at each.b. Indicate the direction of electron flow.c. Label the terminals on the battery as positive or negative and calculate tbe minimum voltage necessary to drive the reaction.
In this electrochemical cell, what is the anode? 1. The solid zinc electrode  2. The Zn2+(aq) ions in the 1 M solution 3. The Cu2+(aq) ions in the 1 M solution 4. The solid copper electrode
Fluoride ion in aqueous are difficult to oxidize at the anode of an electrolytic cell because(A) the aqueous solutions of fluorides are nonconducting.(B) it is impossible to find the proper material from which to build the electrodes.(C) the fluorides are not very soluble.(D) oxygen is released from water in preference to fluorine.
What is produced at each electrode in the electrolysis of an aqueous solution of both NaBr and AgF? Drag the appropriate items to their respective bins. Na(s), H2(g), Ag(s), F2(g), O2(g), Br2(l)
Which of the following statement(s) is/are true?a. Copper metal can be oxidized by Ag + (at standard conditions).b. In a galvanic cell the oxidizing agent in the cell reaction is present at the anode.c. In a cell using the half reactions Al 3+ + 3e- → Al and Mg2+ + 2e- → Mg, aluminum functions as the anode.d. In a concentration cell electrons always flow from the compartment with the lower ion concentration to the compartment with the higher ion concentration.e. In a galvanic cell the negative ions in the salt bridge flow in the same direction as the electrons.
A voltaic cell similar to that shown in Figure 20.5 in the textbook is constructed. One electrode compartment consists of a silver strip placed in a solution of AgNO3, and the other has an iron strip placed in a solution of FeCl2. The overall cell reaction isFe(s) + 2Ag+(aq)  →  Fe2+(aq) + 2Ag(s)What species is oxidized?
Indicate whether each statement is true or false.(a) The anode is the electrode at which oxidation takes place.
A voltaic cell similar to that shown in Figure 20.5 in the textbook is constructed. One electrode compartment consists of a silver strip placed in a solution of AgNO3, and the other has an iron strip placed in a solution of FeCl2. The overall cell reaction isFe(s) + 2Ag+(aq)  →  Fe2+(aq) + 2Ag(s)What species is reduced?
A voltaic cell similar to that shown in Figure 20.5 in the textbook is constructed. One electrode compartment consists of a silver strip placed in a solution of AgNO3, and the other has an iron strip placed in a solution of FeCl2. The overall cell reaction isFe(s) + 2Ag+(aq)  →  Fe2+(aq) + 2Ag(s)Which electrode is the anode, and which is the cathode? What are the signs of the electrodes? Do electrons flow from the silver electrode to the iron electrode, or from the iron to the silver? In which directions do the cations and anions migrate through the solution?
A voltaic cell is constructed. One electrode compartment consists of an aluminum strip placed in a solution of Al ( NO3 )3, and the other has a nickel strip placed in a solution of NiSO4. The overall cell reaction is2Al(s) + 3Ni2+(aq)  →  2Al3+(aq) + 3Ni(s)What species is oxidized?
The ultimate electron acceptor in the respiration process is molecular oxygen. Electron transfer through the respiratory chain takes place through a complex series of oxidation–reduction reactions. Some of the electron transport steps use iron-containing proteins called cytochromes. All cytochromes transport electrons by converting the iron in the cytochromes from the 13 to the 12 oxidation state. Consider the following reduction potentials for three different cytochromes used in the transfer process of electrons to oxygen (the potentials have been corrected for pH and for temperature): cytochrome a(Fe3+) + e- → cytochrome a(Fe2+)      E = 0.385 Vcytochrome b(Fe3+) + e- → cytochrome b(Fe2+)      E = 0.030 Vcytochrome c(Fe3+) + e- → cytochrome c(Fe2+)       E = 0.254 VIn the electron transfer series, electrons are transferred from one cytochrome to another. Using this information, determine the cytochrome order necessary for spontaneous transport of electrons from one cytochrome to another, which eventually will lead to electron transfer to O2.
A voltaic cell is constructed. One electrode compartment consists of an aluminum strip placed in a solution of Al ( NO3 )3, and the other has a nickel strip placed in a solution of NiSO4. The overall cell reaction is2Al(s) + 3Ni2+(aq)  →  2Al3+(aq) + 3Ni(s)What is being reduced?
A voltaic cell is constructed. One electrode compartment consists of an aluminum strip placed in a solution of Al ( NO3 )3, and the other has a nickel strip placed in a solution of NiSO4. The overall cell reaction is2Al(s) + 3Ni2+(aq)  →  2Al3+(aq) + 3Ni(s)Which electrode is the anode, and which is the cathode? What are the signs of the electrodes? Do electrons flow from the aluminum electrode to the nickel electrode, or from the nickel to the aluminum? In which directions do the cations and anions migrate through the solution?
Assume that you want to construct a voltaic cell that uses the following half reactions:A2 +  ( aq ) + 2e-  →  A( s )Eredo= -0.13VB2 +  ( aq ) + 2e-  →  B( s )Eredo= -1.12VYou begin with the incomplete cell pictured below, in which the electrodes are immersed in water.Which electrode functions as the cathode?
Assume that you want to construct a voltaic cell that uses the following half reactions:A2 +  ( aq ) + 2e-  →  A( s )Eredo= -0.13VB2 +  ( aq ) + 2e-  →  B( s )Eredo= -1.12VYou begin with the incomplete cell pictured below, in which the electrodes are immersed in water.Which direction do electrons move through the external circuit?
A voltaic cell that uses the reactionTl3 +  ( aq ) + 2Cr2 +  ( aq )  → Ti+ ( aq ) + 2Cr3 +  ( aq )has a measured standard cell potential of +1.19 V.Sketch the voltaic cell, label the anode and cathode, and indicate the direction of electron flow.
A standard galvanic cell is constructed so that the overall cell reaction is2Al3+ (aq) + 3M (s) → 3M 2+ (aq) + 2Al (s)where M is an unknown metal. If ΔG° = -411 kJ for the overall cell reaction, identify the metal used to construct the standard cell.
Which statement is true for voltaic cells?a) Electrons flow from the anode to the cathode.b) Electrons flow from the more negatively charged electrode to the more positively charged electrode.c) Electrons flow from higher potential energy to lower potential energy.d) All of the above are true.
A voltaic cell that uses the reactionPdCl42-(aq) + Cd(s)   →   Pd(s) + 4Cl-(aq) + Cd2+(aq)has a measured standard cell potential of +1.03 V.Sketch the voltaic cell, label the anode and cathode, and indicate the direction of electron flow by completing the diagram below.
Use the data below to determine which statement is true of the voltaic cell illustrated here.Ag+(aq) + e–  →  Ag(s) E˚ = 0.80 V; Sn2+(aq) + 2 e–  →  Sn(s), E˚ = –0.14 Va) Sn is the anode; Ag is the cathode; electrons flow from left to right.b) Sn is the cathode; Ag is the anode; electrons flow from left to right.c) Sn is the anode; Ag is the cathode; electrons flow from right to left.d) Sn is the cathode; Ag is the anode; electrons flow from right to left.
A concentration cell consists of two Zn/Zn2+ half-cells. The concentration of Zn2+ in one of the half-cells is 2.0 M and the concentration in the other half-cell is 1.0 x 10–3. Label the anode and the cathode. Also show the direction of electron flow
A concentration cell consists of two Zn/Zn2+ half-cells. The concentration of Zn2+ in one of the half-cells is 2.0 M and the concentration in the other half-cell is 1.0 x 10–3. Indicate the half-reaction occurring at each electrode.
Consider the following concentration cell:Label the anode and cathode. Indicate the direction of electron flow.
Consider the following concentration cell:Indicate what happens to the concentration of Pb2+ in each cell.
A voltaic cell consists of a strip of cadmium metal in a solution of Cd ( NO3 )2 in one beaker, and in the other beaker a platinum electrode is immersed in a NaCl solution, with Cl2 gas bubbled around the electrode. A salt bridge connects the two beakers. Use Appendix E in the textbook to find the standard reduction potentials.Which electrode serves as the anode, and which as the cathode?
A voltaic cell consists of a strip of cadmium metal in a solution of Cd ( NO3 )2 in one beaker, and in the other beaker a platinum electrode is immersed in a NaCl solution, with Cl2 gas bubbled around the electrode. A salt bridge connects the two beakers. Use Appendix E in the textbook to find the standard reduction potentials.Does the Cd electrode gain or lose mass as the cell reaction proceeds?
A voltaic cell consists of a strip of cadmium metal in a solution of Cd ( NO3 )2 in one beaker, and in the other beaker a platinum electrode is immersed in a NaCl solution, with Cl2 gas bubbled around the electrode. A salt bridge connects the two beakers. Use Appendix E in the textbook to find the standard reduction potentials.Write the equation for the overall cell reaction.
There are three voltaic cells. In each voltaic cell one half-cell contains a 1.0 M Fe(NO3)2(aq) solution with an Fe electrode. The contents of the other half-cells are as follows:Cell 1: a 1.0 M CuCl2(aq) solution with a Cu electrodeCell 2: a 1.0 M NiCl2(aq) solution with a Ni electrodeCell 3: a 1.0 M ZnCl2(aq) solution with a Zn electrodeIn which voltaic cell(s) does iron act as the anode?
Consider the molecular views of an Al strip and Cu2+ solution. Describe what happens to the atoms and ions after the Al strip is submerged in the solution for a few minutes.
Describe the molecular view of an electrochemical cell involving the overall reaction: Zn(s) + Ni2+(aq) → Zn2+(aq) + Ni(s)
Consider the following galvanic cell:Label the reducing agent and the oxidizing agent, and describe the direction of the electron flow.
Consider the following galvanic cell:a. Label the reducing agent and the oxidizing agent, and describe the direction of the electron flow.
Consider the following galvanic cell:c. Which electrode increases in mass as the reaction proceeds, and which electrode decreases in mass?
Sketch the galvanic cells based on the following overall reactions. Show the direction of electron flow, and identify the cathode and anode. Give the overall balanced equation. Assume that all concentrations are 1.0 M and that all partial pressures are 1.0 atm.a. Cr3+ (aq) + Cl2 (g) ⇌ Cr2O72- (aq) + Cl - (aq)
Sketch the galvanic cells based on the following overall reactions. Show the direction of electron flow, and identify the cathode and anode. Give the overall balanced equation. Assume that all concentrations are 1.0 M and that all partial pressures are 1.0 atm.b. Cu2+ (aq) + Mg (s) ⇌ Mg 2+ (aq) + Cu (s)
Sketch the galvanic cells based on the following overall reactions. Show the direction of electron flow, the direction of ion migration through the salt bridge, and identify the cathode and anode. Give the overall balanced equation. Assume that all concentrations are 1.0 M and that all partial pressures are 1.0 atm.a. IO3- (aq) + Fe2+ (aq) ⇌ Fe3+ (aq) + I 2 (aq)
Sketch the galvanic cells based on the following overall reactions. Show the direction of electron flow, the direction of ion migration through the salt bridge, and identify the cathode and anode. Give the overall balanced equation. Assume that all concentrations are 1.0 M and that all partial pressures are 1.0 atm.b. Zn (s) + Ag+ (aq) ⇌ Zn2+ (aq) + Ag (s)
Which reaction could be used to generate electricity in a voltaic electrochemical cell?a) Pb2+(aq) + Mg(s) → Mg2+(aq) + Pb(s)b) Zn2+(aq) + Sn(s) → Sn2+(aq) + Zn(s)c) NaCl(aq) + AgNO3(aq) → AgCl(s) + NaNO3(aq)d) None of the above
What is the sign of the anode of a voltaic cell?
Do electrons flow toward or away from the anode of a voltaic cell?
What is the sign of the cathode of a voltaic cell?
Do electrons flow toward or away from the cathode of a voltaic cell?
Consider the following voltaic cell:(a) In which direction do electrons flow in the external circuit?
Consider the following voltaic cell:(b) In which half-cell does oxidation occur?
Consider the following voltaic cell:(c) In which half-cell do electrons enter the cell?
Consider the following voltaic cell:(d) At which electrode are electrons consumed?
Consider the following voltaic cell:(e) Which electrode is negatively charged?
Consider the following voltaic cell:(f) Which electrode decreases in mass during cell operation?
Consider the following voltaic cell:(g) Suggest a solution for the electrolyte in the cathode compartment.
Consider the following voltaic cell:(h) Suggest a pair of ions for the salt bridge.
Consider the following voltaic cell:(i) For which electrode could you use an inactive material?
Consider the following voltaic cell:(j) In which direction do anions within the salt bridge move to maintain charge neutrality?
Consider the following voltaic cell:(k) Write balanced half-reactions and the overall cell reaction.
Consider the following voltaic cell:(a) In which direction do electrons flow in the external circuit?
Consider the following voltaic cell:(b) In which half-cell does reduction occur?
Consider the following voltaic cell:(c) In which half-cell do electrons leave the cell?
Consider the following voltaic cell:(d) At which electrode are electrons generated?
Consider the following voltaic cell:(e) Which electrode is positively charged?
Consider the following voltaic cell:(f) Which electrode increases in mass during cell operation?
Consider the following voltaic cell:(g) Suggest a solution for the electrolyte in the anode compartment.
Consider the following voltaic cell:(h) Suggest a pair of ions for the salt bridge.
Consider the following voltaic cell:(i) For which electrode could you use an inactive material?
Consider the following voltaic cell:(j) In which direction do cations within the salt bridge move to maintain charge neutrality?
Consider the following voltaic cell:(k) Write balanced half-reactions and the overall cell reaction.
A voltaic cell is constructed with an Sn/Sn2+ half-cell and a Zn/Zn2+ half-cell. The zinc electrode is negative.(a) Write balanced half-reactions and the overall cell reaction.
A voltaic cell is constructed with an Sn/Sn2+ half-cell and a Zn/Zn2+ half-cell. The zinc electrode is negative.(b) Diagram the cell, labeling electrodes with their charges and showing the directions of electron flow in the circuit and of cation and anion flow in the salt bridge.
Why is a salt bridge necessary in galvanic cells like the one in the following figure?
A voltaic cell is constructed with an Ag/Ag+ half-cell and a Pb/Pb2+ half-cell. The silver electrode is positive.(a) Write balanced half-reactions and the overall cell reaction.
A voltaic cell is constructed with an Ag/Ag+ half-cell and a Pb/Pb2+ half-cell. The silver electrode is positive.(b) Diagram the cell, labeling electrodes with their charges and showing the directions of electron flow in the circuit and of cation and anion flow in the salt bridge.
A voltaic cell is constructed with an Fe/Fe2+ half-cell and an Mn/Mn2+ half-cell. The iron electrode is positive.(a) Write balanced half-reactions and the overall cell reaction.
An active (metal) electrode was found to gain mass as the oxidation-reduction reaction was allowed to proceed. Was the electrode part of the anode or cathode? Explain.
A voltaic cell is constructed with an Fe/Fe2+ half-cell and an Mn/Mn2+ half-cell. The iron electrode is positive.(b) Diagram the cell, labeling electrodes with their charges and showing the directions of electron flow in the circuit and of cation and anion flow in the salt bridge.
A voltaic cell is constructed with a Cu/Cu2+ half-cell and an Ni/Ni2+ half-cell. The nickel electrode is negative.(a) Write balanced half-reactions and the overall cell reaction.
An active (metal) electrode was found to lose mass as the oxidation-reduction reaction was allowed to proceed. Was the electrode part of the anode or cathode? Explain.
A voltaic cell is constructed with a Cu/Cu2+ half-cell and an Ni/Ni2+ half-cell. The nickel electrode is negative.(b) Diagram the cell, labeling electrodes with their charges and showing the directions of electron flow in the circuit and of cation and anion flow in the salt bridge.
The mass of three different metal electrodes, each from a different galvanic cell, were determined before and after the current generated by the oxidation-reduction reaction in each cell was allowed to flow for a few minutes. The first metal electrode, given the label A, was found to have increased in mass; the second metal electrode, given the label B, did not change in mass; and the third metal electrode, given the label C, was found to have lost mass. Make an educated guess as to which electrodes were active and which were inert electrodes, and which were anode(s) and which were the cathode(s).
The overall cell reaction occurring in an alkaline battery isZn(s) + MnO2(s) + H2O(l) ⟶ ZnO(s) + Mn(OH)2(s)(b) If 4.50 g of zinc is oxidized, how many grams of manganese dioxide and of water are consumed?(c) What is the total mass of reactants consumed in part (b)?(e) In practice, voltaic cells of a given capacity (coulombs) are heavier than the calculation in part (c) indicates. Explain.
Using a library or the Internet, research a fuel cell that uses methanol for fuel. What is the overall reaction?
A voltaic cell is constructed with all reactants and products in their standard states. Will the concentration of the reactants increase, decrease, or remain the same as the cell operates?
Consider the following voltaic cell:Determine the direction of electron flow and label the anode and the cathode. Label each electrode as negative or positive.
Consider the following voltaic cell:Determine the direction of electron flow and label the anode and the cathode. Label each electrode, placing the appropriate charge beneath the labels for anode and cathode.
Consider the following voltaic cell:Write a balanced equation for the overall reaction.
A voltaic cell is constructed with two silver-silver chloride electrodes, each of which is based on the following half-reaction:AgCl(s) + e-  →  Ag(s) + Cl- (aq).The two cell compartments have [Cl- ] = 1.51×10−2 M and [Cl- ] = 2.60 M , respectively.Which electrode is the cathode of the cell?
When a clean iron nail is placed in an aqueous solution of copper(II) sulfate, the nail becomes coated with a brownish-black material.(c) Can this reaction be made into a voltaic cell?
Consider a galvanic cell based on the following half-reactions:b. What is the oxidizing agent in the overall cell reaction?
Consider a galvanic cell based on the following half-reactions:c. What substances make up the anode compartment?
Consider a galvanic cell based on the following half-reactions:d. In the standard cell, in which direction do the electrons flow?
Consider a galvanic cell based on the following half-reactions:e. How many electrons are transferred per unit of cell reaction?
Consider the following electrolytic cell.Indicate the half-reaction occurring at Anode.
Consider the following electrolytic cell.Calculate the minimum voltage necessary to drive the reaction.
Draw an electrolytic cell in which Mn2+ is reduced to Mn and Sn is oxidized to Sn2+ (Assume standard conditions). Label the anode and cathode, indicate the direction of electron flow.
Draw an electrolytic cell in which Mn2+ is reduced to Mn and Sn is oxidized to Sn2+ (Assume standard conditions). What minimum voltage is necessary to drive the reaction?
Draw an electrolytic cell in which Mn2+ is reduced to Mn and Sn is oxidized to Sn2+ (Assume standard conditions). Write an equation for the half-reaction occurring at each electrode.
a. In an electrolytic cell Mn2+ is reduced to Mn and Sn is oxidized to Sn2+. Write an equation for the half-reaction occurring at the anode and at the cathode.b. What is the minimum voltage required to drive the reaction in part a.
Two voltaic cells are to be joined so that one will run the other as an electrolytic cell. In the first cell, one half-cell has Au foil in 1.00 M Au(NO3)3, and the other half-cell has a Cr bar in 1.00 M Cr(NO3)3. In the second cell, one half-cell has a Co bar in 1.00 M Co(NO  3)2, and the other half-cell has a Zn bar in 1.00 M Zn(NO3)2.(c) When the electrode wires are switched in one of the cells, which cell will run as the voltaic cell and which as the electrolytic cell?
For the following electrochemical cellCo(s) | Co2+ (aq, 0.0155 M) || Ag+ (aq, 1.50 M) | Ag(s)Write the net cell equation. Phases are optional. Do not include the concentrations.Calculate the following values at 25.0°C using standard potentials as needed.
Magnesium, the element, is produced commercially by electrolysis from a molten salt (the "electrolyte") using a cell similar to the one shown below.Recall that in an electrolytic cell the anode is given the + sign and the cathode is given the - sign, which is the opposite of what we see in batteries. What half-reaction occurs at the anode in this electrolytic cell?
A voltaic cell is based on Ag+(aq)/Ag(s) and Fe3+(aq)/Fe2+(aq) half-cells.Which reaction occurs at the cathode, and which at the anode of the cell?
A 1M solution of Cu ( NO3 )2 is placed in a beaker with a strip of Cu metal. A 1 M solution of SnSO4 is placed in a second beaker with a strip of Sn metal. A salt bridge connects the two beakers, and wires to a voltmeter link the two metal electrodes.Which electrode serves as the anode, and which as the cathode?
Which transformation could take place at the anode of an electrochemical cell?
Identify those elements that can be prepared by electrolysis of their aqueous salts: strontium, gold, tin, chlorine.
Nickel and aluminum electrodes are used to build a galvanic cell. The standard reduction potential for the nickel(II) ion is -0.26 V and that of the aluminum(III) ion is -1.66 V.a. What is the theoretical cell potential assuming standard conditions?b. Which metal is the cathode?c. Which statement is true?     - Electrons flow from Ni to Al.     - Electrons flow from Al to Ni.     - The nickel electrode loses mass.     - The aluminum electrode gains mass.d. Type the shorthand notation for this cell. Do not include concentrations.For example, in shorthand notation your answer might look like Cu|Cu + | |Pd2+|Pd
Co(s) → Co3+(aq) + 3e- (Anode)Ag+(aq) + e- → Ag(s) (Cathode)What is the net cell reaction for the cobalt-silver voltaic cell?Express your answer as a chemical equation. Please include if it is (aq), (l), (s), or (g).
The cell diagram for the lead-acid cell that is used in automobile and truck batteries isPb(s) l PbSO4 (s) l H2SO4 (aq) l PbO2(s), PbSO4(s) l Pb (s)where the comma between PbO2 (s) and PbSO4 (s) denotes a heterogeneous mixture of the two solids and the right-hand lead electrode is nonreactive.a, Write a balanced equation for the net cell reaction:b. Look up standard potentials for the oxidation and the reduction reactions, then calculate the value of E°cell.c. Calculate the value of ΔG°rxnd. Calculate the value of Ecell at 25°C is [H2SO4] = 10.0Me. How many lead-acid cells are in a 12 V car battery? Round to the nearest integer.
Concentration cell based on the Ni2+-Ni cell reaction. (a) Concentrations of Ni2+(aq) in the two half-cells are unequal, and the cell generates an electrical current and a voltage. (b) The cell operates until [Ni2+] is the same in the two half-cells, at which point the cell has reached equilibrium and the emf goes to zero.Which electrode, if any, loses mass as the reaction proceeds?
Which statement is true of all functioning voltaic cells?a) Both Ecell and ∆G are negativeb) Both Ecell and ∆G are positivec) Ecell is negative and ∆G is positived) Ecell is positive and ∆G is negativee) None of the above must be true
a. Label the anode and the cathode. Indicate the direction of electron flow. Label the terminals on the battery as positive or negative.b. Indicate the half-reaction occurring at Anode. Express your answer as a chemical equation. Identify all of the phases in your answer.c. Indicate the half-reaction occurring at Cathode. Express your answer as a chemical equation. Identify all of the phases in your answer.d. Calculate the minimum voltage necessary to drive the reaction. Express your answer using two significant figures.
Sketch a voltaic cell for each redox reaction. Label the anode and cathode and indicate the half-reaction that occurs at each electrode and the species present in each solution. Also indicate the direction of electron flow.c. 2 NO3– (aq) + 8 H+(aq) + 3 Cu(s) → 2 NO(g) + 4 H 2O (/) + 3 Cu2+(aq) 
A 1M solution of Cu ( NO3 )2 is placed in a beaker with a strip of Cu metal. A 1 M solution of SnSO4 is placed in a second beaker with a strip of Sn metal. A salt bridge connects the two beakers, and wires to a voltmeter link the two metal electrodes.Write the equation for the overall cell reaction.
During operation: which half-reaction occurs at the cathode in each type of cell:a. In a battery (voltaic or galvanized cell) reduction occurs at the cathode or oxidation occurs at the cathodeb. In an electrolyte cell reduction occurs at the cathode or oxidation occurs at the cathode
Label the diagram according to the components and processes of a voltaic cell. Drag the appropriate labels to their respective targets.
Which of the following statements is true concerning the voltaic cell shown below? a. The Zn anode mass decreases as the cell discharges.b. The Zn anode mass increases as the cell discharges. c. The Zn cathode mass increases as the cell discharges.d. The Zn cathode mass decreases as the cell discharges. e. The mass of the Zn electrode neither increases nor decreases as the cell discharges.