APChemistryCollege BoardTopic QuestionsUnit 9: Applications of Thermodynamics9.9 Cell Potential Under Nonstandard Conditions

Cell Potential Under Nonstandard Conditions (College Board AP Chemistry)

Topic Questions

DownloadView
Medium
1a1 mark

q3-june-2014---ap-chemistry

A student is given a standard galvanic cell, represented above, that has a Cu electrode and a Sn electrode. As current flows through the cell, the student determines that the Cu electrode increases in mass and the Sn electrode decreases in mass.

Identify the electrode at which oxidation is occurring. Explain your reasoning based on the student’s observations.

How did you do?

1b1 mark

As the mass of the Sn electrode decreases, where does the mass go?

How did you do?

1c2 marks

In the expanded view of the center portion of the salt bridge shown in the diagram below, draw and label a particle view of what occurs in the salt bridge as the cell begins to operate. Omit solvent molecules and use arrows to show the movement of particles.

q3c-june-2014---ap-chemistry

How did you do?

1d2 marks

A nonstandard cell is made by replacing the 1.0 M solutions of Cu(NO3)2 and Sn(NO3)2 in the standard cell with 0.50 M solutions of Cu(NO3)2 and Sn(NO3)2 . The volumes of solutions in the nonstandard cell are identical to those in the standard cell.

i)
Is the cell potential of the nonstandard cell greater than, less than, or equal to the cell potential of the standard cell? Justify your answer.

 

ii)
Both the standard and nonstandard cells can be used to power an electronic device. Would the nonstandard cell power the device for the same time, a longer time, or a shorter time as compared with the standard cell? Justify your answer.

How did you do?

1e4 marks

In another experiment, the student places a new Sn electrode into a fresh solution of 1.0 M Cu(NO3)2 .

Half-Reaction

E ° (V)

Cu+  + e−  → Cu(s)

0.52

Cu2+  + 2 e−  → Cu(s)

0.34

Sn4+  +  2 e−  → Sn2+

0.15

Sn2+  + 2 e−  → Sn(s)

−0.14

 

i)
Using information from the table above, write a net-ionic equation for the reaction between the Sn electrode and the Cu(NO3)2 solution that would be thermodynamically favorable. Justify that the reaction is thermodynamically favorable.

 

ii)
Calculate the value of ΔG° for the reaction. Include units with your answer.

How did you do?

Did this page help you?

2a1 mark

Answer the following questions relating to the element aluminum, Al

Write the complete ground-state electron configuration of an Al atom.

How did you do?

2b1 mark

Based on principles of atomic structure, explain why the radius of the Al atom is larger than the radius of the Al3+ ion.

How did you do?

2c2 marks

A student plans to combine solid aluminum with an aqueous solution of silver ions. The student determines the mass of solid AgNO3 needed to prepare the solution with a specific concentration.

In the following table, briefly list the steps necessary to prepare 200.0 mL of an aqueous solution of AgNO3 using only equipment selected from the choices given. Assume that all appropriate safety measures are already in place. Not all equipment or lines in the table may be needed.

  • Solid AgNO3
  • Weighing paper and scoop
  • 250 mL beakers
  • Distilled water
  • 200.00 mL volumetric flask
  • Pipet
  • Balance
  • 50.0 mL graduated cylinder
  

 

Step Step Description
1. Use weighing paper to measure the determined mass of solid AgNO3 on a balance.
2.  
   
   
   
   

 

How did you do?

2d3 marks

After preparing the solution, the student places some of the solution into a beaker and adds a sample of aluminum. The reaction represented by the following equation occurs.

Al(s) + 3 Ag+(aq)  → Al3+(aq) + 3 Ag(s)   

The following diagram gives an incomplete particulate representation of the reaction. The beaker on the left represents the system before the mixture reacts. Complete the drawing on the right to represent the system after the reaction has occurred. Be sure to include 1) the correct type and number of particles based on the number shown on the left and 2 ) the relative spacing to depict the appropriate phases.

q3-june-2022-ap-chemistry

How did you do?

2e1 mark

The student finds the standard reduction potentials given in the table, which are related to the reaction that occurs.

Half-Reaction E °
Ag+ (aq) + e− →  Ag(s) 0.80 V
 Al3+  (aq) + 3 e−  → Al(s) −1.66 V

 

Using the standard reduction potentials, calculate the value of E ° for the reaction.

How did you do?

2f1 mark

Based on the value of E °, would the standard free energy change of the reaction under standard conditions, ∆G°, be positive, negative, or zero? Justify your answer.

How did you do?

2g1 mark

Once the reaction appears to stop progressing, would the change in free energy, ∆G, be positive, negative, or zero? Justify your answer.

How did you do?

Did this page help you?