Verifying Nernst Equation Calculation: Pb2+ and Ag+

In summary, the conversation discusses using the Nernst equation to find the standard reduction potential for a reaction involving Pb2+ and Ag+. The calculations are checked and it is determined that the standard reduction potential is 0.93V, although the final calculation for E appears to be incorrect.
  • #1
higherme
129
0
Can anyone check if I am doing this right?

Given:
Pb2+ + 2e- ---> Pb(s) E standard = -0.13V
Ag+ + 1e- ---> Ag(s) E standard = 0.80V

[Pb2+] = 0.05M
[Ag+] = 0.5 M these are non standard concentrations

Temp = 298K

Using the Nernst equation, find E


My answer:

Pb oxidized and Ag is reduced ( is this right?... because Ag has the higher reduction potential compared to Pb)

E = E standard - (RT/nF) ln Q

Q = [products]^p/[Reactants]^r

the reaction is: 2Ag+ + Pb(s) + 2e- ---> 2Ag(s) + Pb2 + 2e- (the electrons cancels out)

therefore, Q = (0.05M) / (0.5)^2

Q= 0.20

the E standard = 0.80 - (-0.13) = 0.80 + 0.13 = 0.93V
E = E standard - (RT/nF) ln Q
E = 0.93 - (8.314*298K/2*9.649E4) ln (0.20)
E= 207.56 V

Can anyone check the calculations for me and see if I am doing this right please?

Thank you!
 
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  • #2
higherme said:
Can anyone check if I am doing this right?

Given:
Pb2+ + 2e- ---> Pb(s) E standard = -0.13V
Ag+ + 1e- ---> Ag(s) E standard = 0.80V

[Pb2+] = 0.05M
[Ag+] = 0.5 M these are non standard concentrations

Temp = 298K

Using the Nernst equation, find E


My answer:

Pb oxidized and Ag is reduced ( is this right?... because Ag has the higher reduction potential compared to Pb)

E = E standard - (RT/nF) ln Q

Q = [products]^p/[Reactants]^r

the reaction is: 2Ag+ + Pb(s) + 2e- ---> 2Ag(s) + Pb2 + 2e- (the electrons cancels out)

therefore, Q = (0.05M) / (0.5)^2

Q= 0.20

the E standard = 0.80 - (-0.13) = 0.80 + 0.13 = 0.93V
E = E standard - (RT/nF) ln Q
E = 0.93 - (8.314*298K/2*9.649E4) ln (0.20)
Looks good up to here.

E= 207.56 V
That's way off. Chug those numbers again.
 
  • #3


Your calculations and approach look correct to me. It is always a good idea to check your work and double check your units to ensure accuracy. In this case, the units for R (gas constant) should be in J/mol*K, so the final answer should be 0.20756 V. But overall, it seems like you have correctly applied the Nernst equation and calculated the cell potential for the given concentrations of Pb2+ and Ag+. Good job!
 

1. How do I verify the Nernst equation calculation for Pb2+ and Ag+?

To verify the Nernst equation calculation for Pb2+ and Ag+, you will need to first gather all necessary data such as the standard reduction potentials for both ions, the concentration of each ion, and the temperature at which the calculation is being done. Then, you can plug these values into the Nernst equation and solve for the cell potential. Finally, compare the calculated cell potential with the theoretical value to verify the accuracy of the calculation.

2. What is the purpose of verifying the Nernst equation calculation for Pb2+ and Ag+?

The purpose of verifying the Nernst equation calculation for Pb2+ and Ag+ is to ensure the accuracy and reliability of the results. This is important for the validity and credibility of any scientific experiment or study that involves these ions and their respective reduction potentials.

3. Can the Nernst equation be used for other ions besides Pb2+ and Ag+?

Yes, the Nernst equation can be used for any ion or reaction as long as the necessary data is available. This equation is a fundamental tool in electrochemistry and is frequently used to calculate the cell potential of various reactions.

4. What factors can affect the accuracy of the Nernst equation calculation for Pb2+ and Ag+?

The accuracy of the Nernst equation calculation for Pb2+ and Ag+ can be affected by several factors, such as the purity and concentration of the ions, the temperature of the solution, and any potential errors in the data used in the calculation. It is important to carefully measure and record all data to minimize these sources of error.

5. Are there any limitations to the Nernst equation for Pb2+ and Ag+?

Yes, there are limitations to the Nernst equation for Pb2+ and Ag+. This equation assumes ideal conditions and does not take into account any non-ideal factors such as pH, complexation, and activity coefficients. Therefore, it may not accurately predict the cell potential in real-life situations where these factors are present. Additionally, the Nernst equation only applies to reversible reactions and cannot be used for irreversible reactions.

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