Question 1

All of the following statements concerning voltaic cells are true EXCEPT

Accepted Answer

A)  a salt bridge allows cations and anions to move between the half-cells. 
B)  electrons flow from the cathode to the anode in the external circuit. 
C)  oxidation occurs at the anode. 
D)  a voltaic cell can be used as a source of energy. 
E)  a voltaic cell consists of two-half cells. 
A)  a salt bridge allows cations and anions to move between the half-cells. 
B)  electrons flow from the cathode to the anode in the external circuit. 
C)  oxidation occurs at the anode. 
D)  a voltaic cell can be used as a source of energy. 
E)  a voltaic cell consists of two-half cells.

Question 2

Which of the following reactions would require the use of an inert electrode when used in a voltaic cell?

Accepted Answer

A)  Cu(s)+ 2Ag+(aq) $\to$ 2Ag(s)+ Cu2+(aq) 
B)  3Cu(s)+ 2Au3+(aq) $\to$ 3Cu2+ + 2Au(s) 
C)  Cu(s)+ 2Ag+(aq) $\to$ Cu2+(aq)+ 2Ag(s) 
D)  Co(s)+ 2MnO2(s)+ 2NH4+(aq) $\to$ Co2+(aq)+ Mn2O3(s)+ 2NH3(aq)+ H2O( $\ell$ ) 
E)  3Zn2+(aq)+ 2Al(s) $\to$ 3Zn(s)+ 2Al3+(aq) 
A)  Cu(s)+ 2Ag+(aq) $\to$ 2Ag(s)+ Cu2+(aq) 
B)  3Cu(s)+ 2Au3+(aq) $\to$ 3Cu2+ + 2Au(s) 
C)  Cu(s)+ 2Ag+(aq) $\to$ Cu2+(aq)+ 2Ag(s) 
D)  Co(s)+ 2MnO2(s)+ 2NH4+(aq) $\to$ Co2+(aq)+ Mn2O3(s)+ 2NH3(aq)+ H2O( $\ell$ ) 
E)  3Zn2+(aq)+ 2Al(s) $\to$ 3Zn(s)+ 2Al3+(aq)

Question 3

Calculate the cell potential,at 25 S1U1P1$\circ$S1S1P0C,based upon the overall reaction
Zn2+(aq)+ 2 Fe2+(aq)$\to$ Zn(s)+ 2 Fe3+(aq)
If [Zn2+] = 1.50 $\times$ 10-4 M,[Fe3+] = 0.0200 M,and [Fe2+] = 0.0100 M.The standard reduction potentials are as follows:
Zn2+(aq)+ 2 e- $\to$Zn(s)$~~~~~~~~$ES1U1P1$\circ$S1S1P0 = -0.763 V
Fe3+(aq)+ e- $\to$ Fe2+(aq)$~~~~~~~~$ES1U1P1$\circ$S1S1P0 = +0.771 V

Accepted Answer

A)  -1.665 V 
B)  -1.534 V 
C)  -1.439 V 
D)  -0.008 V 
E)  +0.008 V 
A)  -1.665 V 
B)  -1.534 V 
C)  -1.439 V 
D)  -0.008 V 
E)  +0.008 V

Question 4

How many moles of electrons are produced from a current of 14.4 A in 3.20 hours?

Accepted Answer

A)  4.78 $\times$ 10-4 mol 
B)  1.72 mol 
C)  46.1 mol 
D)  3.35 mol 
E)  9.33 $\times$ 103 mol 
A)  4.78 $\times$ 10-4 mol 
B)  1.72 mol 
C)  46.1 mol 
D)  3.35 mol 
E)  9.33 $\times$ 103 mol

Question 5

The following has a potential of 0.92 V:   If the concentrations of the ions were 1.0 M and the pressure of H2 were 1.0 atm,then ES1U1P1$\circ$S1S1P0  for the half-reaction  
Would be

Accepted Answer

A)  0.46 V 
B)  -0.46 V 
C)  0.92 V 
D)  -0.92 V 
E)  none of these 
A)  0.46 V 
B)  -0.46 V 
C)  0.92 V 
D)  -0.92 V 
E)  none of these

Question 6

The standard cell potential of the following electrochemical cell is 0.19 V.Pt | Sn4+(aq,1.0 M),Sn2+(aq,1.0 M)|| Cu2+(aq,0.200 M)| Cu
Which factor will increase the measured cell potential of the galvanic cell?

Accepted Answer

A)  switching from a platinum to a graphite anode 
B)  increasing the size of the anode 
C)  decreasing the concentration of Cu2+ 
D)  increasing the concentration of Sn4+ 
E)  decreasing the temperature of the cell 
A)  switching from a platinum to a graphite anode 
B)  increasing the size of the anode 
C)  decreasing the concentration of Cu2+ 
D)  increasing the concentration of Sn4+ 
E)  decreasing the temperature of the cell

Question 7

Write a balanced half-reaction for the reduction of CrO42-(aq)to Cr(OH)3(s)in a basic solution.

Accepted Answer

A)  CrO42-(aq)+ 3 OH-(aq)+ 3 e- $\to$Cr(OH)3(s)+ 2 O2(g) 
B)  CrO42-(aq)+ 3 H+(aq)+ 3 e- $\to$ Cr(OH)3(s) 
C)  CrO42-(aq)+ 3 H+(aq)$\to$Cr(OH)3(s)+ 2 e- 
D)  CrO42-(aq)+ 4 H2O(   )+ 3 e- $\to$ Cr(OH)3(s)+ 5 OH-(aq) 
E)  CrO42-(aq)+ 3 OH-(aq)$\to$ Cr(OH)3(s)+ 2 O2(g) 
A)  CrO42-(aq)+ 3 OH-(aq)+ 3 e- $\to$Cr(OH)3(s)+ 2 O2(g) 
B)  CrO42-(aq)+ 3 H+(aq)+ 3 e- $\to$ Cr(OH)3(s) 
C)  CrO42-(aq)+ 3 H+(aq)$\to$Cr(OH)3(s)+ 2 e- 
D)  CrO42-(aq)+ 4 H2O(   )+ 3 e- $\to$ Cr(OH)3(s)+ 5 OH-(aq) 
E)  CrO42-(aq)+ 3 OH-(aq)$\to$ Cr(OH)3(s)+ 2 O2(g)

Question 8

When the following oxidation-reduction reaction in acidic solution is balanced,what is the lowest whole-number coefficient for K+(aq)?
K(s)+ Ca2+(aq) $\to$ K+(aq)+ Ca(s)

Accepted Answer

A)  5 
B)  4 
C)  1 
D)  3 
E)  2 
A)  5 
B)  4 
C)  1 
D)  3 
E)  2

Question 9

Use the standard reduction potentials below to determine which element or ion is the best oxidizing agent.
O2(g)+ 4 H+(aq)+ 4 e- $\to$ 2 H2O(   )$~~~~~~~~$$~~~~~~~~$ES1U1P1$\circ$S1S1P0 = +1.229 V
Hg22+(aq)+ 2 e- $\to$ 2 Hg(   )$~~~~~~~~$$~~~~~~~~$$~~ ~ ~~~$$~ ~~~$ES1U1P1$\circ$S1S1P0 = +0.789 V
I2(s)+ 2 e- $\to$2 I-(aq)$~~~~~~~~$$~~ ~~~~$$~~~~~~~~$$~~~~~~~~$$~~ ~~~~~$ES1U1P1$\circ$S1S1P0 = +0.535 V

Accepted Answer

A)  I2(s) 
B)  O2(g) 
C)  I-(aq) 
D)  Hg22+(aq) 
E)  H2O(   ) 
A)  I2(s) 
B)  O2(g) 
C)  I-(aq) 
D)  Hg22+(aq) 
E)  H2O(   )

Question 10

Given:   $\to$ 
 $~~~~~~~~$$\to$ 
What is the standard Gibbs free-energy change for the following reaction?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 11

Write a balanced chemical equation for the following reaction in an acidic solution.Cr2O72-(aq)+ Ni(s)$\to$Cr3+(aq)+ Ni2+(aq)

Accepted Answer

A)  Cr2O72-(aq)+ 3 Ni(s)+ 14 H+(aq)$\to$ 2 Cr3+(aq)+ 3 Ni2+(aq)+ 7 H2O(   ) 
B)  Cr2O72-(aq)+ Ni(s)+ 14 H+(aq)$\to$ 2 Cr3+(aq)+ Ni2+(aq)+ 7 H2O(   ) 
C)  Cr2O72-(aq)+ 3 Ni(s)$\to$ 2 Cr3+(aq)+ 3 Ni2+(aq)+ O2-(aq) 
D)  Cr2O72-(aq)+ Ni(s)+ 14 H+(aq)$\to$ 2 Cr3+(aq)+ Ni2+(aq)+ 7 H2O(   ) 
E)  Cr2O72-(aq)+ 3 Ni(s)+ 7 H+(aq)$\to$ 2 Cr3+(aq)+ 3 Ni2+(aq)+ 7 OH-(aq) 
A)  Cr2O72-(aq)+ 3 Ni(s)+ 14 H+(aq)$\to$ 2 Cr3+(aq)+ 3 Ni2+(aq)+ 7 H2O(   ) 
B)  Cr2O72-(aq)+ Ni(s)+ 14 H+(aq)$\to$ 2 Cr3+(aq)+ Ni2+(aq)+ 7 H2O(   ) 
C)  Cr2O72-(aq)+ 3 Ni(s)$\to$ 2 Cr3+(aq)+ 3 Ni2+(aq)+ O2-(aq) 
D)  Cr2O72-(aq)+ Ni(s)+ 14 H+(aq)$\to$ 2 Cr3+(aq)+ Ni2+(aq)+ 7 H2O(   ) 
E)  Cr2O72-(aq)+ 3 Ni(s)+ 7 H+(aq)$\to$ 2 Cr3+(aq)+ 3 Ni2+(aq)+ 7 OH-(aq)

Question 12

What is the equilibrium constant (K)at 25°C for the following cell reaction?

Accepted Answer

A)  0.014 
B)  1.7 
C)  0.40 
D)  1.0 
E)  3.0 
A)  0.014 
B)  1.7 
C)  0.40 
D)  1.0 
E)  3.0

Question 13

Assuming the following reaction proceeds in the forward direction,
3 Sn4+(aq)+ 2 Cr(s)$\to$ 3 Sn2+(aq)+ 2 Cr3+(aq)

Accepted Answer

A)  Sn4+(aq)is the reducing agent and Cr(s)is the oxidizing agent. 
B)  Cr(s)is the reducing agent and Sn2+(aq)is the oxidizing agent. 
C)  Sn4+(aq)is the reducing agent and Sn2+(aq)is the oxidizing agent. 
D)  Cr(s)is the reducing agent and Cr3+(aq)is the oxidizing agent. 
E)  Cr(s)is the reducing agent and Sn4+(aq)is the oxidizing agent. 
A)  Sn4+(aq)is the reducing agent and Cr(s)is the oxidizing agent. 
B)  Cr(s)is the reducing agent and Sn2+(aq)is the oxidizing agent. 
C)  Sn4+(aq)is the reducing agent and Sn2+(aq)is the oxidizing agent. 
D)  Cr(s)is the reducing agent and Cr3+(aq)is the oxidizing agent. 
E)  Cr(s)is the reducing agent and Sn4+(aq)is the oxidizing agent.

Question 14

Which of the following equations is a correct form of the Nernst equation?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 15

Write a balanced half-reaction for the reduction of hydrogen peroxide to water in an acidic solution.

Accepted Answer

A)  2 H2O2(   )$\to$ 2 H2O(   )+ O2(g) 
B)  2 H2O2(   )+ 2e- $\to$ 2 H2O(   )+ O2(g) 
C)  H2O2(   )+ 2 H+(aq)+ 2 e- $\to$ 2 H2O(   ) 
D)  H2O2(   )+ 4 H+(aq)+ 2 e- $\to$ 2 H2O(   )+ H2(g) 
E)  H2O2(   )+ 2 H+(aq)+ 4 e- $\to$ 2 H2(g)+ O2(g) 
A)  2 H2O2(   )$\to$ 2 H2O(   )+ O2(g) 
B)  2 H2O2(   )+ 2e- $\to$ 2 H2O(   )+ O2(g) 
C)  H2O2(   )+ 2 H+(aq)+ 2 e- $\to$ 2 H2O(   ) 
D)  H2O2(   )+ 4 H+(aq)+ 2 e- $\to$ 2 H2O(   )+ H2(g) 
E)  H2O2(   )+ 2 H+(aq)+ 4 e- $\to$ 2 H2(g)+ O2(g)

Question 16

The following electrochemical cell has a potential of +0.326 V at 25 S1U1P1$\circ$S1S1P0C.Pt | H2(g,1.00 atm)| H+(aq,1.00 M)|| Cl-(aq)| AgCl(s)| Ag
The standard reduction potential,ES1U1P1$\circ$S1S1P0,of AgCl(s)= +0.222 V.What is the Cl-(aq)concentration?

Accepted Answer

A)  1.9 $\times$ 10-19 M 
B)  5.5 $\times$ 10-10 M 
C)  0.018 M 
D)  1.03 M 
E)  1.8 $\times$ 109 M 
A)  1.9 $\times$ 10-19 M 
B)  5.5 $\times$ 10-10 M 
C)  0.018 M 
D)  1.03 M 
E)  1.8 $\times$ 109 M

Question 17

Given the following standard reduction potentials,
Pb2+(aq)+ 2 e- $\to$ Pb(s)$~~~~~~~~$$~~~~~~~~$$~~~~~~~~$ES1U1P1$\circ$S1S1P0 = -0.126 V
PbSO4(s)+ 2 e- $\to$ Pb(s)+ SO42-(aq)$~~~~~~~~$ES1U1P1$\circ$S1S1P0 = -0.355 V
Determine Ksp for PbSO4(s)at 25 S1U1P1$\circ$S1S1P0C.

Accepted Answer

A)  3.4 $\times$ 10-28 
B)  1.8 $\times$ 10-8 
C)  5.6 $\times$ 10-5 
D)  5.6 $\times$ 107 
E)  2.9 $\times$ 1037 
A)  3.4 $\times$ 10-28 
B)  1.8 $\times$ 10-8 
C)  5.6 $\times$ 10-5 
D)  5.6 $\times$ 107 
E)  2.9 $\times$ 1037

Question 18

A current of 15.0 A is passed through molten magnesium chloride for 15.0 h.How many moles of magnesium metal could be produced via this electrolysis?

Accepted Answer

A)  0.0700 mol 
B)  4.20 mol 
C)  0.37 mol 
D)  0.22 mol 
E)  8.40 mol 
A)  0.0700 mol 
B)  4.20 mol 
C)  0.37 mol 
D)  0.22 mol 
E)  8.40 mol

Question 19

If $\Delta$rGS1U1P1$\circ$S1S1P0 for the following reaction is -22.2 kJ/mol-rxn,calculate   .
Cu2+(aq)+ 2 Ag(s)+ 2 Cl-(aq)$\to$ Cu(s)+ 2 AgCl(s)

Accepted Answer

A)  -0.460 V 
B)  -0.115 V 
C)  +0.115 V 
D)  +0.230 V 
E)  +0.559 V 
A)  -0.460 V 
B)  -0.115 V 
C)  +0.115 V 
D)  +0.230 V 
E)  +0.559 V

Question 20

Which of the following statements concerning a voltaic cell is/are correct?
1)Reduction occurs at the cathode.
2)A spontaneous reaction generates an electric current in a voltaic cell.
3)Without a salt bridge charge buildup will cause the cell reaction to stop.

Accepted Answer

A)  1 only 
B)  2 only 
C)  3 only 
D)  1 and 2 
E)  1,2,and 3 
A)  1 only 
B)  2 only 
C)  3 only 
D)  1 and 2 
E)  1,2,and 3

Exam 20: Principles of Reactivity: Electron Transfer Reactions

All of the following statements concerning voltaic cells are true EXCEPT

Which of the following reactions would require the use of an inert electrode when used in a voltaic cell?

How many moles of electrons are produced from a current of 14.4 A in 3.20 hours?

The following has a potential of 0.92 V: If the concentrations of the ions were 1.0 M and the pressure of H2 were 1.0 atm,then E ∘\circ∘ for the half-reaction Would be

The standard cell potential of the following electrochemical cell is 0.19 V.Pt | Sn4+(aq,1.0 M),Sn2+(aq,1.0 M)|| Cu2+(aq,0.200 M)| Cu Which factor will increase the measured cell potential of the galvanic cell?

Write a balanced half-reaction for the reduction of CrO42-(aq)to Cr(OH)3(s)in a basic solution.

When the following oxidation-reduction reaction in acidic solution is balanced,what is the lowest whole-number coefficient for K+(aq)? K(s)+ Ca2+(aq) →\to→ K+(aq)+ Ca(s)

Given: →\to→ ~~~~~~~~ →\to→ What is the standard Gibbs free-energy change for the following reaction?

Write a balanced chemical equation for the following reaction in an acidic solution.Cr2O72-(aq)+ Ni(s) →\to→ Cr3+(aq)+ Ni2+(aq)

What is the equilibrium constant (K)at 25°C for the following cell reaction?

Assuming the following reaction proceeds in the forward direction, 3 Sn4+(aq)+ 2 Cr(s) →\to→ 3 Sn2+(aq)+ 2 Cr3+(aq)

Which of the following equations is a correct form of the Nernst equation?

Write a balanced half-reaction for the reduction of hydrogen peroxide to water in an acidic solution.

The following electrochemical cell has a potential of +0.326 V at 25 ∘\circ∘ C.Pt | H2(g,1.00 atm)| H+(aq,1.00 M)|| Cl-(aq)| AgCl(s)| Ag The standard reduction potential,E ∘\circ∘ ,of AgCl(s)= +0.222 V.What is the Cl-(aq)concentration?

Given the following standard reduction potentials, Pb2+(aq)+ 2 e- →\to→ Pb(s) ~~~~~~~~ ~~~~~~~~ ~~~~~~~~ E ∘\circ∘ = -0.126 V PbSO4(s)+ 2 e- →\to→ Pb(s)+ SO42-(aq) ~~~~~~~~ E ∘\circ∘ = -0.355 V Determine Ksp for PbSO4(s)at 25 ∘\circ∘ C.

A current of 15.0 A is passed through molten magnesium chloride for 15.0 h.How many moles of magnesium metal could be produced via this electrolysis?

If Δ\DeltaΔ rG ∘\circ∘ for the following reaction is -22.2 kJ/mol-rxn,calculate . Cu2+(aq)+ 2 Ag(s)+ 2 Cl-(aq) →\to→ Cu(s)+ 2 AgCl(s)

Which of the following statements concerning a voltaic cell is/are correct? 1)Reduction occurs at the cathode. 2)A spontaneous reaction generates an electric current in a voltaic cell. 3)Without a salt bridge charge buildup will cause the cell reaction to stop.

Basic Concepts of Chemistry

Mathlets Review: The Tools of Quantitative Chemistry

Atoms, molecules, and Ions

Chemical Reactions

Stoichiometry: Quantitative Information About Chemical Reactions

Principles of Chemical Reactivity: Energy and Chemical Reactions

The Structure of Atoms

The Structure of Atoms and Periodic Trends

Bonding and Molecular Structure

Bonding and Molecular Structure: Orbital Hybridization and Molecular Orbitals

Gases and Their Properties

Intermolecular Forces and Liquids

The Chemistry of Solids

Solutions and Their Behavior

Chemical Kinetics: the Rates of Chemical Reactions

Principles of Reactivity: Chemical Equilibria

The Chemistry of Acids and Bases

Principles of Reactivity: Other Aspects of Aqueous Equilibria

Entropy and Free Energy

Environmental Chemistry Earths Environment,energy,and Sustainability

The Chemistry of the Main Group Elements

The Chemistry of the Transition Elements

Carbon: Not Just Another Element

Biochemistry

Nuclear Chemistry

Filters

The standard cell potential of the following electrochemical cell is 0.19 V.Pt | Sn⁴⁺(aq,1.0 M),Sn²⁺(aq,1.0 M)|| Cu²⁺(aq,0.200 M)| Cu Which factor will increase the measured cell potential of the galvanic cell?

Write a balanced half-reaction for the reduction of CrO₄^2-(aq)to Cr(OH)₃(s)in a basic solution.

When the following oxidation-reduction reaction in acidic solution is balanced,what is the lowest whole-number coefficient for K⁺(aq)? K(s)+ Ca²⁺(aq) $\to$ K⁺(aq)+ Ca(s)

Write a balanced chemical equation for the following reaction in an acidic solution.Cr₂O₇^2-(aq)+ Ni(s) $\to$ Cr³⁺(aq)+ Ni²⁺(aq)

Assuming the following reaction proceeds in the forward direction, 3 Sn⁴⁺(aq)+ 2 Cr(s) $\to$ 3 Sn²⁺(aq)+ 2 Cr³⁺(aq)

The following electrochemical cell has a potential of +0.326 V at 25 ^$\circ$C.Pt | H₂(g,1.00 atm)| H⁺(aq,1.00 M)|| Cl^-(aq)| AgCl(s)| Ag The standard reduction potential,E^$\circ$,of AgCl(s)= +0.222 V.What is the Cl^-(aq)concentration?

Given the following standard reduction potentials, Pb²⁺(aq)+ 2 e^- $\to$ Pb(s) $$ $$ $$ E^$\circ$ = -0.126 V PbSO₄(s)+ 2 e^- $\to$ Pb(s)+ SO₄^2-(aq) $$ E^$\circ$ = -0.355 V Determine K_sp for PbSO₄(s)at 25 ^$\circ$C.