Question 1

For a chemical reaction to be considered for use in a fuel cell, it is absolutely essential for the __________

Accepted Answer

For a fuel cell to work, the chemical reaction must produce a negative free energy change, indicating that the reaction releases energy that can be captured as electrical energy. This energy release is what drives the production of electrical current in a fuel cell. Reactants being solids, liquids, or gases is not the determining factor for a reaction to be used in a fuel cell.

Question 2

A voltaic cell is constructed based on the oxidation of zinc metal and the reduction of silver metal. Solutions of silver nitrate and zinc nitrate also were used. Locate the silver metal on the diagram.

Accepted Answer

The answer of A voltaic cell is constructed based on...

Question 3

A voltaic cell is constructed based on the oxidation of zinc metal and the reduction of silver metal. Solutions of silver nitrate and zinc nitrate also were used. Locate the silver nitrate on the diagram.

Accepted Answer

The answer of A voltaic cell is constructed based on...

Question 4

How do fuel cells differ from traditional electrochemical cells (batteries)?

Accepted Answer

Fuel cells differ from traditional electrochemical cells in that the supply of reactants (usually hydrogen and oxygen) is continually renewed, allowing for continuous energy production. In contrast, traditional batteries have a finite supply of reactants, which are consumed over time, leading to the eventual depletion of the battery's capacity. Fuel cells are also able to operate at higher efficiencies and with lower emissions than traditional combustion-based power sources.

Question 5

How long would it take to electroplate a flute with 28.3 g of silver at a constant current of 2.0 amps using AgNO₃?

Accepted Answer

The correct formula for silver nitrate is likely intended to be AgNO3, but the provided formula seems to be a typographical error. To calculate the time required for electroplating, we use Faraday's laws of electrolysis. The molar mass of silver (Ag) is 107.8682 g/mol, and the charge required to reduce one mole of Ag+ ions is 96,485 C (Coulombs) because silver has a valency of 1. First, calculate the moles of silver to be plated:$$ \text{Moles of Ag} = \frac{28.3 \text{ g}}{107.8682 \text{ g/mol}} $$$$ \text{Moles of Ag} = 0.2624 \text{ mol} $$Next, calculate the total charge needed:$$ \text{Charge} = \text{Moles of Ag} \times \text{Charge per mole of Ag} $$$$ \text{Charge} = 0.2624 \text{ mol} \times 96,485 \text{ C/mol} $$$$ \text{Charge} = 25,336 \text{ C} $$Finally, calculate the time required using the current:$$ \text{Time} = \frac{\text{Charge}}{\text{Current}} $$$$ \text{Time} = \frac{25,336 \text{ C}}{2.0 \text{ A}} $$$$ \text{Time} = 12,668 \text{ s} $$To convert seconds to minutes:$$ \text{Time} = \frac{12,668 \text{ s}}{60 \text{ s/min}} $$$$ \text{Time} \approx 211 \text{ min} $$Therefore, it would take approximately 211 minutes to electroplate the flute with 28.3 g of silver at a constant current of 2.0 amps.

Question 6

The electrodes on batteries are labeled + and -. The __________ is labeled __________, and __________ occurs there.

Accepted Answer

The answer of The electrodes on batteries are labeled +...

Question 7

The oxidation of hydrogen by oxygen is one of the most-used reactions in fuel-cell technology. The overall reaction, which is given below, has a $\Delta$G° value of -474 kJ/mol. What is the standard cell potential for this fuel cell? 2H₂(g) + O₂(g) $\rightarrow$ 2H₂O( )

Accepted Answer

The answer of The oxidation of hydrogen by oxygen is...

Question 8

The oxidation of hydrogen by oxygen is one of the most-used reactions in fuel-cell technology. The overall reaction, which is given below, has a $\Delta$G° value of -237 kJ/mol. What is the standard cell potential for this fuel cell? H₂(g) + O₂(g) $\rightarrow$ H₂O( )

Accepted Answer

The answer of The oxidation of hydrogen by oxygen is...

Question 9

Luke Skywalker found that the batteries for his light-saber were running low. A cryptic inscription on the handle translated roughly into "Four AA dark-side batteries required." The total voltage produced by the four 1.50 V batteries in series therefore was 6.00 volts. If the cell reaction transfers one electron for each mole of the reactants, what is the Gibbs free-energy change for the redox reaction in each of Luke's batteries?

Accepted Answer

The voltage produced by each AA battery is 1.50 V. Therefore, the total voltage produced by four AA batteries in series is 6.00 V. Since the cell reaction transfers one electron for each mole of the reactants, the Gibbs free-energy change can be calculated using the formula

ΔG = -nFE

where ΔG is the Gibbs free-energy change, n is the number of electrons transferred in the cell reaction, F is Faraday's constant (96,485 C/mol), and E is the cell potential.

For each AA battery, n = 1 and E = 1.50 V. Substituting these values into the formula, we get

ΔG = -1 × 96,485 C/mol × 1.50 V = -145,227 J/mol

Converting J/mol to kJ/mol, we get

ΔG = -145 kJ/mol

Therefore, the Gibbs free-energy change for the redox reaction in each of Luke's batteries is -145 kJ/mol.

Question 10

A NiMH battery uses __________ as the reducing agent.

Accepted Answer

NiMH batteries use a metal hydride as the reducing agent.

Question 11

Applying a current to a rechargeable battery converts it from __________ cell to __________ cell.

Accepted Answer

The answer of Applying a current to a rechargeable battery...

Question 12

Which one of the following is not an advantage of lithium batteries?

Accepted Answer

Lithium batteries are favored for their high energy density, which is a result of lithium's extremely negative standard reduction potential, small molar mass, and high mobility in solids. These properties contribute to high battery capacity and large cell potentials, not small ones as suggested in option D.

Question 13

Copper metal is purified by electrolysis. How much copper metal could be produced from copper(II) oxide by applying a current of 10.0 amps at the appropriate negative potential for 12.0 hours?

Accepted Answer

The amount of copper metal produced can be calculated using Faraday's constant (F) and the equation:
moles of electrons transferred = current (in amperes) × time (in seconds) ÷ Faraday's constant
Using the molar mass of CuO and stoichiometry, we can convert moles of electrons to moles of CuO, and then to mass of Cu:
CuO + H2O → Cu + O2 + H2O
1 mol e^- (or 1 F) transfers 2 mol of Cu:
2 mol Cu / 1 mol e^-
The appropriate negative potential for the reduction of CuO is -0.34 V (from a table of standard reduction potentials).
F = 96485 C/mol e^- (or 96485 A·s/mol e^-)
10.0 A × (12.0 h × 3600 s/h) = 4.32 × 10^5 C
moles of electrons transferred = 4.32 × 10^5 C ÷ 96485 C/mol e^- = 4.48 mol e^-
moles of Cu produced = 0.5 × 4.48 mol e^- = 2.24 mol Cu
mass of Cu produced = 2.24 mol × 63.55 g/mol = 142 g

Question 14

A voltaic cell is constructed based on the oxidation of zinc metal and the reduction of silver metal. Solutions of silver nitrate and zinc nitrate also were used. Locate the zinc nitrate on the diagram.

Accepted Answer

The answer of A voltaic cell is constructed based on...

Question 15

Aluminum metal is refined in a very energy-intensive process from bauxite ore using the Hall process, which requires electrolysis of aluminum oxide, Al₂O₃, in molten cryolyte at more than 1012°C. In an industrial electrolysis cell, 1900 kg of aluminum oxide was reduced with a current of 1500 amps. How long did it take to reduce all the reactant to aluminum metal?

Accepted Answer

The answer of Aluminum metal is refined in a very...

Question 16

Which of the following is not an advantage in using hydrogen fuel cells rather than gasoline engines in vehicles?

Accepted Answer

Storage of hydrogen fuel is actually more dangerous than gasoline due to its high flammability and the need for high-pressure tanks to store it safely.

Question 17

Which statement regarding battery-powered electric cars is not correct? Currently battery-powered electric cars __________.

Accepted Answer

The answer of Which statement regarding battery-powered electric cars is...

Question 18

When a voltaic cell reaches equilibrium, __________

Accepted Answer

The answer of When a voltaic cell reaches equilibrium, __________
...

Question 19

A NiMH battery uses __________ as the oxidizing agent.

Accepted Answer

NiMH batteries use nickel oxyhydroxide (NiO(OH)) as the oxidizing agent, which is represented by choice E.

Question 20

What is true when a battery (voltaic cell) is dead?

Accepted Answer

The answer of What is true when a battery (voltaic...

Quiz 19: Electrochemistry and the Quest for Clean Energy

For a chemical reaction to be considered for use in a fuel cell, it is absolutely essential for the __________

A voltaic cell is constructed based on the oxidation of zinc metal and the reduction of silver metal. Solutions of silver nitrate and zinc nitrate also were used. Locate the silver metal on the diagram.

A voltaic cell is constructed based on the oxidation of zinc metal and the reduction of silver metal. Solutions of silver nitrate and zinc nitrate also were used. Locate the silver nitrate on the diagram.

How do fuel cells differ from traditional electrochemical cells (batteries) ?

How long would it take to electroplate a flute with 28.3 g of silver at a constant current of 2.0 amps using AgNO₃?

The electrodes on batteries are labeled + and -. The is labeled , and __ occurs there.

A NiMH battery uses __________ as the reducing agent.

Applying a current to a rechargeable battery converts it from cell to cell.

Which one of the following is not an advantage of lithium batteries?

Copper metal is purified by electrolysis. How much copper metal could be produced from copper(II) oxide by applying a current of 10.0 amps at the appropriate negative potential for 12.0 hours?

A voltaic cell is constructed based on the oxidation of zinc metal and the reduction of silver metal. Solutions of silver nitrate and zinc nitrate also were used. Locate the zinc nitrate on the diagram.

Which of the following is not an advantage in using hydrogen fuel cells rather than gasoline engines in vehicles?

Which statement regarding battery-powered electric cars is not correct? Currently battery-powered electric cars __________.

When a voltaic cell reaches equilibrium, __________

A NiMH battery uses __________ as the oxidizing agent.

What is true when a battery (voltaic cell) is dead?

Quiz 19: Electrochemistry and the Quest for Clean Energy

For a chemical reaction to be considered for use in a fuel cell, it is absolutely essential for the __________

A voltaic cell is constructed based on the oxidation of zinc metal and the reduction of silver metal. Solutions of silver nitrate and zinc nitrate also were used. Locate the silver metal on the diagram.

A voltaic cell is constructed based on the oxidation of zinc metal and the reduction of silver metal. Solutions of silver nitrate and zinc nitrate also were used. Locate the silver nitrate on the diagram.

How do fuel cells differ from traditional electrochemical cells (batteries) ?

How long would it take to electroplate a flute with 28.3 g of silver at a constant current of 2.0 amps using AgNO3?

The electrodes on batteries are labeled + and -. The __________ is labeled __________, and __________ occurs there.

The oxidation of hydrogen by oxygen is one of the most-used reactions in fuel-cell technology. The overall reaction, which is given below, has a Δ\DeltaΔ G° value of -474 kJ/mol. What is the standard cell potential for this fuel cell? 2H2(g) + O2(g) →\rightarrow→ 2H2O( )

The oxidation of hydrogen by oxygen is one of the most-used reactions in fuel-cell technology. The overall reaction, which is given below, has a Δ\DeltaΔ G° value of -237 kJ/mol. What is the standard cell potential for this fuel cell? H2(g) + O2(g) →\rightarrow→ H2O( )

A NiMH battery uses __________ as the reducing agent.

Applying a current to a rechargeable battery converts it from __________ cell to __________ cell.

Which one of the following is not an advantage of lithium batteries?

Copper metal is purified by electrolysis. How much copper metal could be produced from copper(II) oxide by applying a current of 10.0 amps at the appropriate negative potential for 12.0 hours?

A voltaic cell is constructed based on the oxidation of zinc metal and the reduction of silver metal. Solutions of silver nitrate and zinc nitrate also were used. Locate the zinc nitrate on the diagram.

Which of the following is not an advantage in using hydrogen fuel cells rather than gasoline engines in vehicles?

Which statement regarding battery-powered electric cars is not correct? Currently battery-powered electric cars __________.

When a voltaic cell reaches equilibrium, __________

A NiMH battery uses __________ as the oxidizing agent.

What is true when a battery (voltaic cell) is dead?

How long would it take to electroplate a flute with 28.3 g of silver at a constant current of 2.0 amps using AgNO₃?

The electrodes on batteries are labeled + and -. The is labeled , and __ occurs there.

Applying a current to a rechargeable battery converts it from cell to cell.