How does Changing Salt Bridge Solution affect observed voltages?

In summary, the observed cell potential would not be affected by changing the salt bridge solution from Potassium nitrate to Zinc nitrate, but the potential difference may change depending on whether Zn2+ is the anode or cathode in the half cell.
  • #1
faradayslaw
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Homework Statement


In a lab in which many half-cells are constructed, one of which contains Zn2+, the original salt bridge solution is Potassium nitrate. Suppose we needed to change this solution to Zinc nitrate. What would be the effect on the observed cell potentials?


Homework Equations


Reduction Potential of Zn2+ = +0.76 V
Ecell=Ecathode-Eanode

The Attempt at a Solution


So it seemed at first that the observed voltages would not be altered in all half cells except that with the Zn 2+ ions, since the Zn 2+ ions are not involved in the half-cell reactions, but on the other hand, the high reduction potential of Zn2+ may lead to Zn2+ reducing, rather than the actual metal cations in the anode.

Moreover, for the Zn2+ half cell, the potential difference would increase if the Zn2+ was the anode, and would decrease if Zn2+ was in the cathode.

Please let me know if this is the correct way to think about the problem

Thanks,
 
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  • #2
Salt bridge doesn't change electrode reactions, however, different solution may have different resistance.
 

1. How does changing the concentration of the salt bridge solution affect the observed voltages?

Changing the concentration of the salt bridge solution can affect the observed voltages by altering the ionic strength of the solution. This can impact the flow of ions between the two half-cells, leading to a change in the potential difference and therefore the observed voltage.

2. What is the relationship between the type of salt used in the bridge solution and the observed voltages?

The type of salt used in the bridge solution can affect the observed voltages by influencing the specific ions present in the solution. Different ions have different charge and size, which can affect the potential difference between the two half-cells and thus the observed voltage.

3. Does changing the temperature of the salt bridge solution have an impact on the observed voltages?

Yes, changing the temperature of the salt bridge solution can have an impact on the observed voltages. Temperature can affect the rate of the chemical reactions occurring in the half-cells, which can in turn affect the potential difference and therefore the observed voltage.

4. How does the length of the salt bridge solution affect the observed voltages?

The length of the salt bridge solution can affect the observed voltages by changing the resistance of the solution. A longer salt bridge will have a higher resistance, which can impact the flow of ions and thus the potential difference between the two half-cells.

5. Is there a specific pH range for the salt bridge solution that yields the most accurate observed voltages?

Yes, there is a specific pH range for the salt bridge solution that yields the most accurate observed voltages. Generally, a pH of around 7 is ideal as it ensures that the solution is neutral and does not interfere with the reactions occurring in the half-cells.

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