CHEM 1225 Chapter 18

Which statements about electrolysis are correct? Select all that apply.

Electrolysis is used to drive a nonspontaneous reaction. Electrolysis requires a constant input of energy.

Which of the following factors increase the rate of corrosion? Select all that apply.

Increasing electrolyte concentration Increasing the temperature

Which of the following options gives the overall equation for the mercury battery?

Zn(Hg) + HgO(s) → ZnO(s) + Hg(l)

If one were to construct a galvanic cell consisting of two Zn2+/Zn electrodes at two different concentrations, the more concentrated cell will be the _____.

cathode

Calcium is plated onto an electrode through the reduction reaction Ca2+(aq) + 2e- → Ca(s). Which equation would be used to calculate the mass of calcium that is deposited in 30.0 seconds at using a current of 2.0 A? The Faraday constant F = 96,500 C/mol.

(2.0A)(30.0s)(1molCa2mole-)(40.1gCamolCa)(96,500Cmole-)

Given that the standard potential for the half-reaction Ag+(aq) + e- → Ag(s); Eo = +0.80 V, calculate the standard reduction potential for the half-reaction 2Ag+(aq) + 2e- → 2Ag(s).

+0.80 V

Co3+(aq) + Cu(s) → Co2+(aq) + Cu+(aq) Calculate the standard cell potential for the reaction above, given the following information: Co3+(aq) + e- → Co2+(aq); Eo = 1.842 V Cu+(aq) + e- → Cu(s); Eo = 0.521 V

+1.321 V

Calculate the standard free-energy change for the reaction shown below. 2Fe2+(aq) + H2O2(aq) + 2H+(aq) → 2H2O(l) + 2Fe3+(aq); Eocell = 1.00 V, F = 96,500 J/V⋅mol

-193 kJ

Ca(s) + Mg2+(aq) → Ca2+(aq) + Mg(s); Eo = 0.50 V Mg2+(aq) + 2e- → Mg(s); Eo = -2.37 V Using the standard cell potential given above and the standard reduction potential listed above, calculate the reduction potential of the half-reaction Ca2+(aq) + 2e- → Ca(s).

-2.87 V

Given that the standard potential for the half-reaction Ca2+(aq) + 2e- → Ca(s) is -2.87 V, what is the standard potential for the half-reaction 2Ca2+(aq) + 4e- → 2 Ca(s)?

-2.87 V

A current of 2.50 A is used to plate aluminum onto an object according to the reaction Al3+(aq) + 3e- → Al(s). What mass of aluminum will be produced over a period of 14.0 minutes? The Faraday constant F = 96,500 C/mol.

0.196 g

Which statement about electrical potential and electrical charge is correct?

1 volt is equal to 1 joule per coulomb.

When hydrogen atoms are balanced in the following (unbalanced) half-reaction, identify the amount of the substance that must be introduced, and where it will appear in the equation. Assume the reaction occurs in acidic medium.

12 H+ must be added as a reactant.

Prior to balancing oxygen and hydrogen atoms, identify the missing coefficients in the following half-reaction:

1:1

Identify the missing coefficient to balance Mn in the following half-reaction (do not worry about balancing the oxygen atoms). Mn2O3 → _____ MnO2

2

Identify the number of water molecules needed to balance the following half-reaction. Also indicate whether the water will appear as a reactant or a product.

2 H2O; product

Identify the number of electrons required to balance the following half-reaction. Also indicate whether these electrons must appear as reactants or products.

2 e-; reactant

When hydrogen and oxygen atoms are balanced in the following half-reaction under acidic conditions, which of the following statements are correct? Select all that apply.

2 moles of H2O appear as a product. 4 moles of H+ appear as a reactant.

In order to balance the two half-reactions below to each other, the first reaction should be multiplied by _____, and the second reaction should be multiplied by _____.

2, 3

Iron is produced by electrolysis of aqueous Fe2(SO4)3. How many coulombs of charge are required per mole of Fe produced? The Faraday constant F = 96,500 C/mol.

2.90 x 105 C

What is the spontaneous reaction that occurs when the following half-cells are combined? Cr3+(aq) + 3e- → Cr(s); Eo = -0.74 V Fe2+(aq) + 2e- → Fe(s); Eo = -0.44 V

2Cr(s) + 3Fe2+(aq) → 2Cr3+(aq) + 3Fe(s)

Which of the following half-reactions could occur at the cathode of a galvanic cell? Select all that apply.

2H+(aq) + 2e- → H2(g) Ni2+(aq) + 2e- → Ni(s)

How many moles of electrons are transferred in the electrochemical reaction represented by the balanced equation Cr(s) + 3Ag+(aq) → Cr3+(aq) + 3Ag(s)?

3

When the two half-reactions below are added together (ensuring that the electrons cancel), which of the following is the net reaction?

3Cu2+ + 2Fe → 3Cu + 2Fe3+

How many moles of electrons are transferred when the two half-reactions shown below are combined to generate the spontaneous balanced chemical reaction with the lowest possible integer coefficients? Cu2+(aq) 2e- → Cu(s); Eo +0.34 V Cr2O72-(aq) + 4H+(aq) + 6e- → 2Cr3+(aq) + 7H2O(l) Eo = +1.33 V

6 moles of e-

If the value of Eocell is < 0 for a given reaction, then the value of K is ______, and the reaction is ______ under standard conditions.

< 1; nonspontaneous

If the value of ΔGo is < 0 for a given reaction, then the value of K is ______, and the reaction is ______ under standard conditions.

> 1; spontaneous

Which of the following options correctly describe a battery? Select all that apply.

A battery is a series of connected galvanic cells that provides electric current. A battery exploits a spontaneous redox reaction to generate electrical energy.

What is the spontaneous reaction that occurs when the two half-cells below are combined? Fe3+(aq) + e- → Fe2+(aq); Eo = 0.77 V Ag+(aq) + e- → Ag(s); Eo = 0.80 V

Ag+(aq) + Fe2+(aq) → Ag(s) + Fe3+(aq)

If we were to solve for the cell potential of the following reaction, which two reactions would we first need to find in a standard reduction table? 2Ag+(aq) + Zn(s) → 2Ag(s) + Zn2+(aq)

Ag+(aq) + e- → Ag(s) Zn2+(aq) + 2e- → Zn(s)

Which of the following is the proper shorthand notation for the redox reaction Cr3+(aq) + Al(s) → Al3+(aq) + Cr(s)?

Al(s) | Al3+(aq) || Cr3+(aq) | Cr(s)

The Faraday constant allows one to convert between moles of and the equivalent amount of charge in units of

Blank 1: electrons Blank 2: coulombs, C, or coulomb

The movement of one or more from one reactant to another is the key chemical event in an oxidation - reaction, also called a(n) reaction.

Blank 1: electrons, electron, e-, or electron(s) Blank 2: reduction Blank 3: redox or electron-transfer

The equation ΔG = -nFEcell relates the energy of an electrochemical reaction to its cell

Blank 1: free or Gibbs free Blank 2: potential, voltage, emf, or electromotive force

By definition, if one coulomb of charge passes between two electrodes that differ in potential by one volt, one of energy is released. This relationship is correctly expressed as V = per . (Fill in units only, without values.)

Blank 1: joule or J Blank 2: J, joule, or joules Blank 3: C or coulomb

The Nernst equation is used to calculate the cell potential under conditions. The cell potential is found to differ from the standard cell potential by a factor proportional to the natural log of the reaction (Q).

Blank 1: nonstandard, non-standard, non standard, nonstandard-state, or non-standard state Blank 2: quotient

If a substance causes another substance to be oxidized, that substance is a(n) agent. Likewise, the substance that is oxidized in an electrochemical reaction is always the agent.

Blank 1: oxidizing Blank 2: reducing

In a table of standard reduction potentials, the reactants are a list of potential ___ agents, while the products are a list of potential ___ agents.

Blank 1: oxidizing Blank 2: reducing

In conventional cell notation for a galvanic cell, a single vertical line represents a(n) ___boundary, while a double vertical line represents the ___ ___ . Listen to the complete question

Blank 1: phase Blank 2: salt Blank 3: bridge

The measure of energy used in electrochemistry is the cell ____ (Ecell), which is the difference in electrical potential between two electrodes. A common term for this difference in electrical potential is ___ force or emf.

Blank 1: potential or voltage Blank 2: electromotive

The total free energy (ΔG) for a given process represents the maximum amount of that can be done by the process.

Blank 1: work or useful work

In the electrolysis of molten CaBr2 using inert electrodes, ______ will be produced at the anode, while ______ will be produced at the cathode.

Br2(l); Ca(s)

In which of the following reactions is chlorine reduced? Select all that apply.

Cl2 + 2Na → 2NaCl 2NaClO + F2 → NaF + Cl2 + O2

The standard reduction potential for the half-reaction Mn2+(aq) + 2e- → Mn(s) is -1.18 V. What is the effect on the reduction potential of doubling all of the coefficients of the half-reaction?

Doubling the coefficients has no effect on the reduction potential.

Which of the following is required to solve for the nonstandard cell potential, using the Nernst equation? Select all that apply.

E°, the standard cell potential Q, the reaction coefficient n (the number of electrons in the balanced reaction)

True or false: For a spontaneous redox reaction, the products are stronger oxidizing and reducing agents than the reactants.

False

True or false: In the electrolysis of an aqueous solution of KBr, Br- is the only substance present that can be oxidized.

False

Which of the following statements correctly describe the reactions occurring in a hydrogen-oxygen fuel cell? Select all that apply.

H2(g) is oxidized at the anode. O2(g) is the reactant at the cathode in the fuel cell.

For the chemical reaction shown below, which of the following (unbalanced) reactions should be used as the starting point for the reduction half-reaction?

H2O → H2

When a redox reaction that takes place in an acidic solution involves an oxygen imbalance, oxygen should be balanced by adding _____ as needed, while hydrogen should be balanced by adding _____.

H2O; H+

The reaction below is spontaneous in the forward direction. Which of the statements below provides the best reason for this observation? Ni(s) + 2Ag+(aq) → Ni2+(aq) + 2Ag(s)

Ni(s) gives its electrons away more freely than Ag(s).

Given the two half-reactions below, which reaction will be the reduction reaction in the spontaneous reaction that would occur between them? Cr3+ + 3e- → Cr; Eo = -0.74 V Ni2+ + 2e- → Ni; Eo = -0.28 V

Ni2+ + 2e- → Ni

Which of the following options correctly describes how to use a table of standard reduction potentials to write the equation for the half-reaction that occurs at the anode?

Reverse the appropriate reduction half-reaction.

Which of the following reactions result in the oxidation of sulfur? Select all that apply.

S8 + 8O2 → 8SO2 SO2 + H2O2 → H2SO4

In which of the following examples has the oxidation number (O.N.) of the given element been assigned correctly? Select all that apply.

The O.N. for chlorine in the ion ClO3- is +5. The O.N. for iron in FeO is +2.

Which of the following best explains why the following chemical reaction is not balanced?

The charge is not balanced.

The two electrodes of an electrolytic cell are placed in a sample of molten zinc iodide. After a time, reddish-brown I2(s) begins to form at one electrode while gray Zn(s) deposits on the other. Which of the following options correctly describe the process occurring? Select all that apply.

The half-reaction occurring at the anode is represented by 2I-(l) → I2(s) + 2e-. At the cathode, Zn2+ ions are reduced to form Zn(s).

When zinc metal is immersed in a 1.0 M solution of copper(II) chloride at 25oC, no electrochemical work may be extracted, even though a spontaneous reaction occurs. What is wrong this this cell design?

The oxidation and reduction reactions must be physically separated.

Which of the following are the focus of electrochemistry? Select all that apply.

The relationship between chemical change and electrical work The interconversion of electrical and chemical energy

A metal object is to be plated with Cr metal by electrolysis of aqueous Cr2(SO4)3. Determine the number of electrons transferred and the total charge per mole of Cr(s) produced.

The total charge is 3 x 96,500 = 2.90 x 105 C. 3 mol e- per mole of Cr(s)

Which of the following statements correctly describe a redox reaction? Select all that apply.

This type of reaction involves the transfer of electrons. Reduction and oxidation always occur together.

True or false: An oxidation number is not the same as an actual charge on an ion.

True

In the diagram, electrons flow from the _____ electrode to the _____ electrode. Cations flow from the _____ cell to the _____ cell.

Zn; Cu; anode; cathode

In a lithium-ion battery, lithium ions migrate from the _____ to the _____ in order to balance the total charge as electrons pass through the external circuit.

anode; cathode

A self-contained device that consists of a series of combined galvanic cells that can be used as a source of direct electric current at constant voltage is called a(n)

battery

For a table of standard reduction potentials that is listed with the most positive cell potentials at the top of the list, any species on the left of a given half-cell reaction will react spontaneously with a species that appears on the right of any half-cell reaction located _____ it.

below

An oxidation number is the _____ an atom would have if all bonds involved the _____ of electrons. The oxidation number can be used to track movement of electrons in chemical reactions.

charge; transfer

A species that is reduced ____ electrons and becomes ____ positive. Its oxidation number will ____.

gains; less; decrease

A(n) _____ cell exploits a spontaneous redox reaction to generate electrical energy, whereas a(n) _____ cell requires a continuous input of electrical energy.

galvanic; electrolytic

The Nernst equation relates the value of Ecell to the reaction quotient Q. As an electrochemical reaction proceeds toward products, the value of Q will ______, and the value of Ecell will ______.

increase; decrease

A species that is oxidized ____ electrons and becomes ____ positive. Its oxidation number will ____.

loses; more; increases

Oxidation is defined as the _____ of electrons while reduction is the _____ of electrons.

loss; gain

If due to a change in reaction conditions the standard cell potential (Eo) of an electrochemical reaction becomes more negative, the standard free-energy change (ΔGo) will become _____, and the equilibrium constant (Keq) will become _____.

more positive; smaller

The difference between the calculated voltage (based on standard potentials) and the actual voltage required to cause electrolysis is called ______.

overvoltage

When predicting the spontaneous reaction between two different half-cells, the reaction with the most negative cell potential will be the _____ reaction, while the reaction with the most positive cell potential will be the _____ reaction.

oxidation; reduction

A species acts as a(n) _____ agent if it gains electrons in a half-reaction. Conversely, it could potentially act as a(n) _____ agent if it loses electrons in a half-reaction.

oxidizing; reducing

If a substance acts as a strong oxidizing agent, it will appear on a table of standard reduction potentials as the _____ in a half-reaction with a _____ standard reduction potential.

reactant; positive

If ΔGo < 0, the reaction is _____ as written; if K < 1, the reaction is _____ as written.

spontaneous; nonspontaneous

By convention, a positive value for Eocell means that the cell reaction will be ______ as written under standard conditions. The more positive the value of Eocell, the greater the ratio of ______ at equilibrium.

spontaneous; products to reactants

Which of the following options correctly expresses the relationship between free-energy change and cell potential?

ΔG = -nFEcell

How is the change in free energy (ΔG) of a chemical system related to work?

ΔG represents the maximum useful work that a reaction can supply.

A standard electrochemical cell is constructed from an anode that has a standard reduction potential of -2.0 V and a cathode that has a standard reduction potential of +0.5 V. Which of the following is the correct expression to calculate the standard cell potential?

+0.5 + 2.0

Calculate the standard free-energy change for the reaction shown below. MnO2(s) + 4H+(aq) + 2Cl-(aq) → 2H2O(l) + Mn2+(aq) + Cl2(g); Eocell = -0.13 V, F = 96,500 J/V⋅mol

+25 kJ

Given the data below, what will be the standard cell potential for a Cr/Fe voltaic cell?

+30

Sn(s) + Sn4+(aq) → 2Sn2+(aq); Eo = 0.290 V Sn4+(aq) + 2e- → Sn2+(aq); Eo = +0.154 V Using the standard cell potential given above and the standard reduction potential listed above, calculate the standard reduction potential for the half-reaction Sn2+(aq) + 2e- → Sn(s).

-0.136 V

Fe(s) + Hg22+(aq) → Fe2+(aq) + 2Hg(l); Eo = 1.229 V Hg22+(aq) + 2e- → 2Hg(l); Eo = +0.789 V Using the standard cell potential given above and the standard reduction potential listed above, calculate the standard reduction potential for the half-reaction Fe2+(aq) + 2e- → Fe(s).

-0.440 V

An aqueous solution of CuBr2 is placed in an electrolytic cell. Which of the following reactions may occur at the cathode? Select all that apply.

2H2O(l) + 2e- → H2(g) + 2OH-(aq) Cu2+(aq) + 2e- → Cu(s)

In which reaction shown is oxygen being oxidized?

2H2O(l) → 2H2(g) + O2(g)

What is the spontaneous reaction that occurs when the following half-cells are combined? Zn2+(aq) + 2e- → Zn(s); Eo = -0.76V Na+(aq) + e- → Na(s); Eo = -2.71 V

2Na(s) + Zn2+(aq) → 2Na+(aq) + Zn(s)

Based on the information given, which reaction would require an electrolytic cell in order to occur? Br2(l) + 2e- → 2Br-(aq); Eo = +1.07 V 2H2O(l) + 2e- → 2OH-(aq) + H2(g); Eo = -0.83 V

2NaBr(aq) + 2H2O(l) → 2NaOH(aq) + H2(g) + Br2(aq)

A concentration cell is constructed based on the equation Ag+ (1.0 M) + Ag(s) → Ag(s) + Ag+ (x M). When a silver electrode is immersed into this cell at 25.0oC, and it is tested against a 1.0 M AgNO3/Ag electrode, a 0.250-V cell potential develops. Calculate the concentration of the electrolyte in the anode compartment.

6.03 x 10-5 M

Which of the following statements correctly describe half-reactions? Select all that apply.

A half-reaction shows the electrons involved in a redox reaction. A half-reaction represents an oxidation or a reduction reaction.

Which of the following options correctly describe the shorthand notation used to represent an electrochemical cell? Select all that apply.

A single vertical line in cell notation represents a phase boundary. The anode is written first, on the left side of the cell notation

Which of the following statements about oxidation, reduction, and oxidizing/reducing agents are correct? Select all that apply.

A species that loses electrons is oxidized. A species whose oxidation number increases is acting as a reducing agent. A species that gains electrons is acting as an oxidizing agent.

Which of the following correctly describe the electrolysis of water? Select all that apply.

An electrolyte such as H2SO4 is required for this reaction. Hydrogen gas is generated at the cathode.

The standard ___ potential for a half-reaction is the voltage associated with the reduction reaction at an electrode when all solutes are at a concentration of 1 M and gases are at ___ atm of pressure.

Blank 1: reduction Blank 2: 1 or one

The cell potential for the standard hydrogen electrode (SHE) is by definition equal to ___ volts. If this half-cell is used as the anode, and all of the substances in the cathode are under standard conditions, then the potential of the cell is equal to the standard ___ potential of the cathode.

Blank 1: zero, 0, 0.0, or 0.00 Blank 2: reduction

Which of the following statements correctly describe standard electrode potentials? Select all that apply.

By convention, standard electrode potentials are quoted as reduction potentials. Standard reduction potentials are measured for solutes at 1 M and gases at 1 atm.

Which of the following options correctly describe corrosion? Select all that apply.

During corrosion the metal surface supplies both the cathode and the anode. During corrosion, a metal is oxidized. Some metals oxidize to form a protective coating, which prevents further corrosion.

Which of the following are valid forms of the Nernst equation, which relates cell potential under nonstandard conditions to the standard cell potential? Select all that apply.

E = Eo - 0.0592Vn0.0592Vn log Q (at 298 K) E = Eo - RTnFRTnF ln Q

In general, when the concentration of the reactants in an electrochemical reaction is large, and the concentration of products is small, which of the following will be true regarding the relationship between Ecell and Ecello?

Ecell > Eocell

A galvanic cell is constructed according to the the following notation: Cr(s)|Cr3+(aq) || Fe2+(aq)|Fe(s) The initial concentrations of Fe2+ and Cr3+ are 2.00 M and 0.100 M, respectively. Which of the following statements about the values of Q and Ecell are correct? Select all that apply.

Ecell is greater than Eocell. Q = 1.25 x 10-3

Which of the following must be balanced when balancing a redox reaction? Select all that apply.

Electrical charges Electrons transferred Atoms

Which of the following options correctly describe the units used to express electrical potential, charge, and electrical energy? Select all that apply.

Electrical energy can be measured in joules. The volt is the unit for electrical potential.

True or false: The equation for a redox reaction is balanced in exactly the same way as any other chemical equation.

False

To which of the following half-reactions must 2 electrons appear as products in order to balance the equation?

H2O + PbO → PbO2 + 2H+ H2 + 2OH- → 2H2O

If ΔGo for a reaction is equal to 0, what must be true regarding the equilibrium constant?

K = 1

The redox reaction below is spontaneous as written. Which statement about the relative roles and strengths of the components of the reaction is correct? Mg(s) + 2Cu+(aq) → Mg2+(aq) + 2Cu(s)

Mg2+ is the weaker oxidizing agent.

When the two half-reactions below are added together (ensuring that the electrons cancel), which of the following is the net reaction?

MnO2 + 4H+ + 2Cu + 2I- → Mn2+ + 2CuI + 2H2O

Which of the following options correctly describe the most common dry cell battery? Select all that apply.

MnO2 is a component of the battery. Zn is the anode in this cell.

In which of the following (unbalanced) half-reactions will 1 mole of water appear as a reactant when oxygen atoms are balanced? Select all that apply.

N2O5 → 2NO3 Na → NaOH

Na+ + e- → Na; Eo = -2.7 V Cl2 + 2 e- → 2 Cl-; Eo = 1.4 V Consider the reactions occurring in an electrolytic cell at two inactive electrodes immersed in anhydrous molten sodium chloride. Which products form at the cathode and anode?

Na forms at the cathode; Cl2 forms at the anode.

Which of the following options describe the additional step(s) required to balance a redox reaction that takes place in a basic solution (as opposed to an acidic solution)? Select all that apply.

OH- must be added to each side of the equation in order to react with H+. Each OH- ion added will combine with one H+ that is on the same side of the equation to form H2O.

A voltaic cell is constructed from the two half-reactions whose standard reductions potentials are shown. What reaction will occur at the anode? Pb2+ + 2e- → Pb; Eo = -0.13 V Co3+ + 3e- → Co; Eo = +1.57 V

Pb → Pb2+ + 2e-

Which of the following statements correctly describe the rules for assigning oxidation numbers? Select all that apply.

The oxidation number for a monatomic ion is the same as its charge. The sum of the oxidation numbers for the atoms in a neutral compound is zero.

Using a current of 4.75 A, a sculpture is copper plated with 1.50 g of Cu by electrolysis of a CuSO4 solution. Which of the following options correctly reflect the processes required to calculate the time required for this process? Select all that apply. The Faraday constant F = 96,500 C/mol.

The process will take 16.0 minutes. There are 4.72 x 10-2 moles of electrons transferred. The half-reaction is Cu2+(aq) + 2e- → Cu(s).

Which of the following options correctly identify the abbreviation for cell potential and its units? Select all that apply.

The unit of cell potential is the volt, symbol V. The symbol for cell potential is E.

When water is hydrolyzed in the presence of NaCl, the possible half-cell equations are given in the accompanying table. Experimentally, it is found that H2(g) and Cl2(g) are formed, while O2(g) and Na(s) are not. What is the best explanation for this?

There is a significant overvoltage associated with the oxidation of water to form oxygen.

When calcium ions (Ca2+) are electrolytically reduced to calcium metal, what is the relationship between the moles of electrons transferred and the moles of Ca(s) produced?

Two mol of e- will be transferred for every 1 mol Ca(s) produced.

The reaction shown below occurs in a basic solution. Select all the options that correctly describe the balanced equation obtained after all resulting species are combined and/or canceled correctly.

Two moles of H2O appear among the reactants. Four moles of OH- appear among the products.

In addition to having the same number and type of ______ on both sides of the arrow, a redox reaction must also have the same total ______ on both sides of the arrow.

atoms; charge

In a galvanic cell, positively charged ions migrate from the salt bridge to the ______ compartment, while negatively charged ions migrate from the salt bridge to the ______ compartment.

cathode; anode

The standard cell potential may be solved using the equation E o ______ - E o _____. Select all the options that will correctly complete the equation given.

cathode; anode reduction; oxidation

A galvanic cell that is constructed using the same electrode in both half-cells with different ion concentrations in each half-cell is called a(n) cell.

concentration

The deterioration of metals by an electrochemical process is called . The metal is oxidized during this process.

corrosion

The SI unit of current is the ampere, which is defined as the flow of charge in units of _____ over a period of time measured in _____.

coulombs; seconds

With regard to species on a table of standard reduction potentials, the ______ rule states that any substance on the left-hand side of a half-reaction will react with any substance below it on the right-hand side.

diagonal

The half-reactions in a redox process ______.

each represent one-half of the electron transfer process

The process in which electrical energy is used to drive a nonspontaneous electrochemical reaction is called .

electrolysis

When a redox reaction is balanced the number of ______ lost by the species being oxidized must be ______ the number of these particles gained by the species being reduced.

electrons; equal to

The maximum amount of useful work a chemical system can supply is related to the value of the _____ for the reaction.

free-energy change

A battery consists of one or more ______ cells that deliver electrical energy at a constant ______.

galvanic; voltage

An oxidation number ____. (Select all that apply.)

is assigned by treating all bonds as if they were ionic is the same as an oxidation state is used to identify oxidation or reduction of a species

When writing a spontaneous redox reaction from two half-reactions in a table of standard reduction potentials, the half-reaction occurring at the anode will be the half-reaction whose reduction potential in the table is ______ positive. In the spontaneous reaction, the direction of this half-reaction will be ______ its direction in the table.

less; reversed from

A redox reaction _____. (Select all that apply.)

may involve covalent species involves both oxidation and reduction involves electron transfer

A sacrificial anode can be used to protect a metal like iron from corrosion. In order for this to work, the anode must be _____ than the metal that it is protecting.

more active

The Nernst equation is used to determine the value of Ecell for an electrochemical reaction under ______ conditions; the difference between Ecell and Eocell is a function of ______.

nonstandard; Q

As listed in a table of standard electrode potentials, the reactants in the half-reactions are potential _____ agents, while the products of the half-reactions are potential _____ agents.

oxidizing; reducing

If a substance acts as a strong reducing agent, it will appear on a table of standard reduction potentials as the _____ in a half-reaction with a _____ standard reduction potential.

product; negative

An oxidation half-reaction will have one or more electrons on the ____ side of the equation, while a reduction half-reaction will have one or more electrons on the ____ side of the equation.

product; reactant

Consider the half-reaction with the most negative standard reduction potential in a given table. The ______ in that half-reaction will be the strongest ______ agent among the substances in the table.

product; reducing

The oxidation of one species allows the reduction of another, so the species being oxidized is called the _____ agent while the species being reduced is the _____ agent.

reducing; oxidizing

Standard potentials for electrochemical half-reactions are expressed as ______ potentials. They are measured at a standard temperature of ______ oC.

reduction; 25

The cell potential of a galvanic cell is ______.

the voltage across the two electrodes