Lesson test: Electrochemical cells

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Electrochemical cells

1.[2p]
Using $E^{ominus} = - 0.76$ V for $Z / Zn$ and $+ 0.34$ V for $C / Cu$ , what is the standard potential of the Daniell cell, in volts?

CorrectNot quite: 1.10

2.[3p]
That cell transfers two electrons. What is $Δ_{r} G^{ominus}$ in kJ mol⁻¹, taking $F = 96485$ C mol⁻¹?

CorrectNot quite: -212

3.[3p]
Why is a half reaction's standard potential unchanged when the equation is doubled?

Potential is energy per unit charge, so doubling the reaction doubles both

Correct

The table only lists one-electron reactions

The answer is: Potential is energy per unit charge, so doubling the reaction doubles both

Doubling a reaction is not allowed

The answer is: Potential is energy per unit charge, so doubling the reaction doubles both

The potential is measured against hydrogen, which cancels the factor

The answer is: Potential is energy per unit charge, so doubling the reaction doubles both

4.[3p]
A Daniell cell has $[Z] = 1.0$ and $[C] = 0.010$ mol dm⁻³. Using $E = E^{ominus} - (0.0592 / n) \log_{10} Q$ with $E^{ominus} = 1.10$ V, what is its potential in volts?

CorrectNot quite: 1.04

5.[2p]
A flat battery is a cell whose reaction has reached equilibrium.

True

Correct

False

The answer is: True

6.[2p]
What does the salt bridge in a galvanic cell do?

Carries ions between the two solutions to keep both electrically neutral

Correct

Carries electrons from the anode to the cathode

The answer is: Carries ions between the two solutions to keep both electrically neutral

Stops the two solutions from mixing at all

The answer is: Carries ions between the two solutions to keep both electrically neutral

Supplies the reactants for the cell reaction

The answer is: Carries ions between the two solutions to keep both electrically neutral

7.[3p]
How many coulombs are needed to produce one kilogram of aluminium by $A + 3 e^{-} \to Al$ , taking the molar mass as $26.982$ g mol⁻¹ and $F = 96485$ C mol⁻¹?

CorrectNot quite: 1.07e7

8.[3p]
Zinc blocks bolted to a steel hull protect it from corrosion. Why?

Zinc has a more negative potential, so it becomes the anode and corrodes instead

Correct

Zinc forms a physical barrier over the whole hull

The answer is: Zinc has a more negative potential, so it becomes the anode and corrodes instead

Zinc neutralises the seawater

The answer is: Zinc has a more negative potential, so it becomes the anode and corrodes instead

Zinc has a more positive potential and takes electrons from the iron

The answer is: Zinc has a more negative potential, so it becomes the anode and corrodes instead

9.[2p]
Match each cell to its working voltage.

Lead-acid cell
Lithium-ion cell
Hydrogen fuel cell
Daniell cell

1.10 V
1.23 V
2.05 V
3.6 V

Show the answer

Lead-acid cell: 2.05 V Lithium-ion cell: 3.6 V Hydrogen fuel cell: 1.23 V Daniell cell: 1.10 V

1.[2p] Using Eominus=-0.76 V for Z/Zn and +0.34 V for C/Cu, what is the standard potential of the Daniell cell, in volts?

2.[3p] That cell transfers two electrons. What is ΔrGominus in kJ mol⁻¹, taking F=96485 C mol⁻¹?

3.[3p] Why is a half reaction's standard potential unchanged when the equation is doubled?

4.[3p] A Daniell cell has [Z]=1.0 and [C]=0.010 mol dm⁻³. Using E=Eominus-(0.0592/n)log10Q with Eominus=1.10 V, what is its potential in volts?

5.[2p] A flat battery is a cell whose reaction has reached equilibrium.

6.[2p] What does the salt bridge in a galvanic cell do?

7.[3p] How many coulombs are needed to produce one kilogram of aluminium by A+3e-→Al, taking the molar mass as 26.982 g mol⁻¹ and F=96485 C mol⁻¹?

8.[3p] Zinc blocks bolted to a steel hull protect it from corrosion. Why?

9.[2p] Match each cell to its working voltage.

1.[2p]
Using $E^{ominus} = - 0.76$ V for $Z / Zn$ and $+ 0.34$ V for $C / Cu$ , what is the standard potential of the Daniell cell, in volts?

2.[3p]
That cell transfers two electrons. What is $Δ_{r} G^{ominus}$ in kJ mol⁻¹, taking $F = 96485$ C mol⁻¹?

3.[3p]
Why is a half reaction's standard potential unchanged when the equation is doubled?

4.[3p]
A Daniell cell has $[Z] = 1.0$ and $[C] = 0.010$ mol dm⁻³. Using $E = E^{ominus} - (0.0592 / n) \log_{10} Q$ with $E^{ominus} = 1.10$ V, what is its potential in volts?

5.[2p]
A flat battery is a cell whose reaction has reached equilibrium.

6.[2p]
What does the salt bridge in a galvanic cell do?

7.[3p]
How many coulombs are needed to produce one kilogram of aluminium by $A + 3 e^{-} \to Al$ , taking the molar mass as $26.982$ g mol⁻¹ and $F = 96485$ C mol⁻¹?

8.[3p]
Zinc blocks bolted to a steel hull protect it from corrosion. Why?

9.[2p]
Match each cell to its working voltage.