Question 1

The standard cell potential (E°_cell)of the reaction below is +0.126 V.The value of for the reaction is ________ kJ/mol. Pb (s)+ 2H⁺(aq)→ Pb²⁺ (aq)+ H₂ (g)

Accepted Answer

The answer of The standard cell potential (E°_cell)of the reaction...

Question 2

The standard cell potential (E°_cell)of the reaction below is -0.55 V.The value of for the reaction is ________ J/mol. I₂ (s)+ 2Br^- (aq)→ 2I^- (aq)+ Br₂ (l)

Accepted Answer

The equation to calculate 11ea7e7c_6192_17ed_9a0a_b9d2421702f8_TB1194_11 is:

11ea7e7c_6192_17ed_9a0a_b9d2421702f8_TB1194_11 = -nFE°

where n is the number of moles of electrons transferred in the reaction, F is the Faraday constant (96,485 C/mol), and E° is the standard cell potential.

In the given reaction, two electrons are transferred, so n = 2. Plugging in the given values, we get:

11ea7e7c_6192_17ed_9a0a_b9d2421702f8_TB1194_11 = -2 * 96485 * (-0.55)

11ea7e7c_6192_17ed_9a0a_b9d2421702f8_TB1194_11 = 1.066 * 10^5 J/mol

Rounding to two significant figures, we get 1.1 × 10^5 J/mol, which is answer choice D.

Question 3

The less ________ the value of E°_red,the lower the driving force for reduction.

Accepted Answer

The less positive the value of E° (standard reduction potential), the lower the driving force for reduction, as a more positive E° indicates a greater tendency for a species to gain electrons (be reduced).

Question 4

In a voltaic cell,electrons flow from the ________ to the ________.

Accepted Answer

Electrons flow from the anode (where oxidation occurs) to the cathode (where reduction occurs) in a voltaic cell. So, option E, "anode, cathode" is the correct choice.

Question 5

The half-reaction occurring at the anode in the balanced reaction shown below is ________. 3MnO₄^- (aq)+ 24H⁺ (aq)+ 5Fe (s)→ 3Mn²⁺ (aq)+ 5Fe³⁺ (aq)+ 12H₂O (l)

Accepted Answer

The anode is where oxidation occurs, and in this reaction, iron (Fe) is oxidized to Fe^3+, releasing electrons, which matches choice C.

Question 6

The standard cell potential (E°_cell)of the reaction below is -0.34 V.The value of for the reaction is ________ kJ/mol. Cu (s)+ 2H⁺ (aq)→ Cu²⁺ (aq)+ H₂ (g)

Accepted Answer

The answer of The standard cell potential (E°_cell)of the reaction...

Question 7

The balanced half-reaction in which sulfate ion is reduced to sulfite ion is a ________ process.

Accepted Answer

The reduction of sulfate ion (SO4^2-) to sulfite ion (SO3^2-) involves the gain of two electrons, making it a two-electron process.

Question 8

The balanced half-reaction in which ethanol,CH₃CH₂OH,is oxidized to ethanoic acid,CH₃COOH. is a ________ process.

Accepted Answer

The balanced half-reaction for the oxidation of ethanol to ethanoic acid involves the loss of 4 electrons per molecule of ethanol. This can be seen from the following equation:

CH3CH2OH → CH3COOH + 4e-

Therefore, the process is a four-electron process.

Question 9

The standard cell potential (E°_cell)for the voltaic cell based on the reaction below is ________ V. 2Cr (s)+ 3Fe²⁺ (aq)→ 3Fe (s)+ 2Cr³⁺ (aq)

Accepted Answer

The answer of The standard cell potential (E°_cell)for the voltaic...

Question 10

The balanced half-reaction in which dichromate ion is reduced to chromium metal is a ________ process.

Accepted Answer

The reduction of dichromate ion (Cr2O7^2-) to chromium metal (Cr) involves a twelve-electron process. This is because each Cr in the dichromate ion gains six electrons to become Cr metal, and since there are two Cr atoms involved, the total is twelve electrons.

Question 11

The reduction half reaction occurring in the standard hydrogen electrode is ________.

Accepted Answer

The reduction half reaction occurring in the standard hydrogen electrode is the reduction of a hydrogen ion to form hydrogen gas, which is represented as 2H+ + 2e- → H2. This is the only reaction listed in option D that fits this description. Options A and B involve the oxidation of sulfur, while option C involves the reduction of oxygen. Option E involves a redox reaction between hydrogen and chlorine, but is not relevant to the standard hydrogen electrode.

Question 12

________ electrons appear in the following half-reaction when it is balanced. S₄O₆^2- → 2S₂O₃^2-

Accepted Answer

The answer of ________ electrons appear in the following half-reaction...

Question 13

The relationship between the change in Gibbs free energy and the emf of an electrochemical cell is given by ________.

Accepted Answer

This equation, known as the Nernst equation, relates the change in Gibbs free energy to the electromotive force (emf) of an electrochemical cell. It takes into account the number of electrons transferred (n), the Faraday constant (F), and the emf of the cell (E). The negative sign in the equation indicates that a positive emf corresponds to a negative change in Gibbs free energy, which means that the reaction is spontaneous.

Question 14

The electrode at which oxidation occurs is called the ________.

Accepted Answer

The electrode at which oxidation occurs is called the anode.

Question 15

1V = ________.

Accepted Answer

1 volt is defined as the difference in electric potential across a conductor when an electric current of one ampere dissipates one watt of power. Therefore, it equals one joule per coulomb (1 J/C).

Question 16

The standard cell potential (E°_cell)for the voltaic cell based on the reaction below is ________ V. Cr (s)+ 3Fe³⁺ (aq)→ 3Fe²⁺ (aq)+ Cr³⁺ (aq)

Accepted Answer

The standard cell potential can be calculated using the formula: E°cell = E°reduction (cathode) - E°reduction (anode). We need to find the standard reduction potentials for each half-reaction and subtract them. The half-reactions are:
Cr3+(aq) + 3e- → Cr(s)..... E°reduction = -0.74 V
Fe3+(aq) + e- → Fe2+(aq)..... E°reduction = +0.77 V
S2O32-(aq) + 2e- → 2S2-(aq)..... E°reduction = -0.32 V
The reduction potential for the half-reaction involving Cr is negative and it is being oxidized while Fe and S are being reduced. Therefore, we need to flip the first half-reaction and change the sign of its reduction potential to get the oxidation potential.
Cr(s) → Cr3+(aq) + 3e-..... E°oxidation = +0.74 V
Now we can calculate the standard cell potential:
E°cell = E°reduction (cathode) - E°reduction (anode)
E°cell = (3 x E°reduction (Fe2+)) + E°reduction (S2-) - (E°oxidation (Cr))
E°cell = (3 x 0.77 V) + (-0.32 V) - 0.74 V
E°cell = 1.51 V
Therefore, the best choice is C: +1.51 V.

Question 17

The standard cell potential (E°_cell)for the voltaic cell based on the reaction below is ________ V. Sn²⁺ (aq)+ 2Fe³⁺ (aq)→ 2Fe²⁺ (aq)+ Sn⁴⁺ (aq)

Accepted Answer

To calculate the standard cell potential, we need to add the standard reduction potentials of the half-reactions:
Sn4+ + 2e- → Sn2+ | E° = -0.14 V (reduction at anode)
Fe3+ + e- → Fe2+ | E° = +0.77 V (reduction at cathode)

E°cell = E°reduction (cathode) - E°reduction (anode) = +0.77 - (-0.14) = +0.617 V (since the reaction is spontaneous, the standard cell potential is positive)

Question 18

The standard cell potential (E°_cell)for the voltaic cell based on the reaction below is ________ V. 3Sn⁴⁺ (aq)+ 2Cr (s)→ 2Cr³⁺ (aq)+ 3Sn²⁺ (aq)

Accepted Answer

The standard cell potential can be calculated by subtracting the standard reduction potential of the anode (or oxidizing agent) from the standard reduction potential of the cathode (or reducing agent). Looking up the standard reduction potentials in a table, we get:
Cr3+(aq) + e- -> Cr2+(aq)    E° = -0.40 V
Sn4+(aq) + 2e- -> Sn2+(aq)  E° = +0.15 V
Therefore, the standard cell potential is:
E°cell = E°cathode - E°anode
= (+0.15 V) - (-0.40 V)
= +0.55 V
Note that the reaction equation must be balanced first and that the identity of the reagents in your figure (SnS1U1P14 or Sn4+, for example) appears to be erroneous.

Question 19

The balanced half-reaction in which chlorine gas is reduced to the aqueous chloride ion is a ________ process.

Accepted Answer

When chlorine gas is reduced to chloride ion, it gains two electrons: Cl2 + 2e- → 2Cl-. Therefore, the balanced half-reaction is a two-electron process, and choice B is the correct answer.

Question 20

The half-reaction occurring at the cathode in the balanced reaction shown below is ________. 3MnO₄^- (aq)+ 24H⁺ (aq)+ 5Fe (s)→ 3Mn²⁺ (aq)+ 5Fe³⁺ (aq)+ 12H₂O (l)

Accepted Answer

The answer of The half-reaction occurring at the cathode in...

Quiz 20: Electrochemistry

The standard cell potential (E°_cell) of the reaction below is +0.126 V.The value of for the reaction is ________ kJ/mol. Pb (s) + 2H⁺(aq) → Pb²⁺ (aq) + H₂ (g)

The standard cell potential (E°_cell) of the reaction below is -0.55 V.The value of for the reaction is ________ J/mol. I₂ (s) + 2Br^- (aq) → 2I^- (aq) + Br₂ (l)

The less ________ the value of E°_red,the lower the driving force for reduction.

In a voltaic cell,electrons flow from the to the .

The half-reaction occurring at the anode in the balanced reaction shown below is ________. 3MnO₄^- (aq) + 24H⁺ (aq) + 5Fe (s) → 3Mn²⁺ (aq) + 5Fe³⁺ (aq) + 12H₂O (l)

The standard cell potential (E°_cell) of the reaction below is -0.34 V.The value of for the reaction is ________ kJ/mol. Cu (s) + 2H⁺ (aq) → Cu²⁺ (aq) + H₂ (g)

The balanced half-reaction in which sulfate ion is reduced to sulfite ion is a ________ process.

The balanced half-reaction in which ethanol,CH₃CH₂OH,is oxidized to ethanoic acid,CH₃COOH. is a ________ process.

The standard cell potential (E°_cell) for the voltaic cell based on the reaction below is ________ V. 2Cr (s) + 3Fe²⁺ (aq) → 3Fe (s) + 2Cr³⁺ (aq)

The balanced half-reaction in which dichromate ion is reduced to chromium metal is a ________ process.

The reduction half reaction occurring in the standard hydrogen electrode is ________.

________ electrons appear in the following half-reaction when it is balanced. S₄O₆^2- → 2S₂O₃^2-

The relationship between the change in Gibbs free energy and the emf of an electrochemical cell is given by ________.

The electrode at which oxidation occurs is called the ________.

1V = ________.

The standard cell potential (E°_cell) for the voltaic cell based on the reaction below is ________ V. Cr (s) + 3Fe³⁺ (aq) → 3Fe²⁺ (aq) + Cr³⁺ (aq)

The standard cell potential (E°_cell) for the voltaic cell based on the reaction below is ________ V. Sn²⁺ (aq) + 2Fe³⁺ (aq) → 2Fe²⁺ (aq) + Sn⁴⁺ (aq)

The standard cell potential (E°_cell) for the voltaic cell based on the reaction below is ________ V. 3Sn⁴⁺ (aq) + 2Cr (s) → 2Cr³⁺ (aq) + 3Sn²⁺ (aq)

The balanced half-reaction in which chlorine gas is reduced to the aqueous chloride ion is a ________ process.

The half-reaction occurring at the cathode in the balanced reaction shown below is ________. 3MnO₄^- (aq) + 24H⁺ (aq) + 5Fe (s) → 3Mn²⁺ (aq) + 5Fe³⁺ (aq) + 12H₂O (l)

Quiz 20: Electrochemistry

The standard cell potential (E°cell) of the reaction below is +0.126 V.The value of for the reaction is ________ kJ/mol. Pb (s) + 2H+(aq) → Pb2+ (aq) + H2 (g)

The standard cell potential (E°cell) of the reaction below is -0.55 V.The value of for the reaction is ________ J/mol. I2 (s) + 2Br- (aq) → 2I- (aq) + Br2 (l)

The less ________ the value of E°red,the lower the driving force for reduction.

In a voltaic cell,electrons flow from the ________ to the ________.

The half-reaction occurring at the anode in the balanced reaction shown below is ________. 3MnO4- (aq) + 24H+ (aq) + 5Fe (s) → 3Mn2+ (aq) + 5Fe3+ (aq) + 12H2O (l)

The standard cell potential (E°cell) of the reaction below is -0.34 V.The value of for the reaction is ________ kJ/mol. Cu (s) + 2H+ (aq) → Cu2+ (aq) + H2 (g)

The balanced half-reaction in which sulfate ion is reduced to sulfite ion is a ________ process.

The balanced half-reaction in which ethanol,CH3CH2OH,is oxidized to ethanoic acid,CH3COOH. is a ________ process.

The standard cell potential (E°cell) for the voltaic cell based on the reaction below is ________ V. 2Cr (s) + 3Fe2+ (aq) → 3Fe (s) + 2Cr3+ (aq)

The balanced half-reaction in which dichromate ion is reduced to chromium metal is a ________ process.

The reduction half reaction occurring in the standard hydrogen electrode is ________.

________ electrons appear in the following half-reaction when it is balanced. S4O62- → 2S2O32-

The relationship between the change in Gibbs free energy and the emf of an electrochemical cell is given by ________.

The electrode at which oxidation occurs is called the ________.

1V = ________.

The standard cell potential (E°cell) for the voltaic cell based on the reaction below is ________ V. Cr (s) + 3Fe3+ (aq) → 3Fe2+ (aq) + Cr3+ (aq)

The standard cell potential (E°cell) for the voltaic cell based on the reaction below is ________ V. Sn2+ (aq) + 2Fe3+ (aq) → 2Fe2+ (aq) + Sn4+ (aq)

The standard cell potential (E°cell) for the voltaic cell based on the reaction below is ________ V. 3Sn4+ (aq) + 2Cr (s) → 2Cr3+ (aq) + 3Sn2+ (aq)

The balanced half-reaction in which chlorine gas is reduced to the aqueous chloride ion is a ________ process.

The half-reaction occurring at the cathode in the balanced reaction shown below is ________. 3MnO4- (aq) + 24H+ (aq) + 5Fe (s) → 3Mn2+ (aq) + 5Fe3+ (aq) + 12H2O (l)

The standard cell potential (E°_cell) of the reaction below is +0.126 V.The value of for the reaction is ________ kJ/mol. Pb (s) + 2H⁺(aq) → Pb²⁺ (aq) + H₂ (g)

The standard cell potential (E°_cell) of the reaction below is -0.55 V.The value of for the reaction is ________ J/mol. I₂ (s) + 2Br^- (aq) → 2I^- (aq) + Br₂ (l)

The less ________ the value of E°_red,the lower the driving force for reduction.

In a voltaic cell,electrons flow from the to the .

The half-reaction occurring at the anode in the balanced reaction shown below is ________. 3MnO₄^- (aq) + 24H⁺ (aq) + 5Fe (s) → 3Mn²⁺ (aq) + 5Fe³⁺ (aq) + 12H₂O (l)

The standard cell potential (E°_cell) of the reaction below is -0.34 V.The value of for the reaction is ________ kJ/mol. Cu (s) + 2H⁺ (aq) → Cu²⁺ (aq) + H₂ (g)

The balanced half-reaction in which ethanol,CH₃CH₂OH,is oxidized to ethanoic acid,CH₃COOH. is a ________ process.

The standard cell potential (E°_cell) for the voltaic cell based on the reaction below is ________ V. 2Cr (s) + 3Fe²⁺ (aq) → 3Fe (s) + 2Cr³⁺ (aq)

________ electrons appear in the following half-reaction when it is balanced. S₄O₆^2- → 2S₂O₃^2-

The standard cell potential (E°_cell) for the voltaic cell based on the reaction below is ________ V. Cr (s) + 3Fe³⁺ (aq) → 3Fe²⁺ (aq) + Cr³⁺ (aq)

The standard cell potential (E°_cell) for the voltaic cell based on the reaction below is ________ V. Sn²⁺ (aq) + 2Fe³⁺ (aq) → 2Fe²⁺ (aq) + Sn⁴⁺ (aq)

The standard cell potential (E°_cell) for the voltaic cell based on the reaction below is ________ V. 3Sn⁴⁺ (aq) + 2Cr (s) → 2Cr³⁺ (aq) + 3Sn²⁺ (aq)

The half-reaction occurring at the cathode in the balanced reaction shown below is ________. 3MnO₄^- (aq) + 24H⁺ (aq) + 5Fe (s) → 3Mn²⁺ (aq) + 5Fe³⁺ (aq) + 12H₂O (l)