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Perplexity Ai:
Why is the Salt Bridge Is Necessary for Current to Flow in a Galvanic Cell?
Maintaining Electrical Neutrality
The salt bridge is essential in a galvanic (voltaic) cell because it maintains the electrical neutrality of the solutions in both half-cells as the redox reaction proceeds.
During operation:
At the anode (e.g., copper in the image), metal atoms lose electrons (oxidation), forming positive ions that enter the solution. This increases the positive charge in the anode compartment.
At the cathode (e.g., silver), positive metal ions in solution gain electrons (reduction) and deposit as metal, decreasing the positive charge in the cathode compartment.
Without a salt bridge, these charge imbalances would quickly build up: one half-cell would become increasingly positive, and the other increasingly negative. This charge separation would oppose further electron flow, effectively stopping the redox reaction and halting current through the external circuit.
Completing the Electrical Circuit
The salt bridge contains a solution of inert electrolyte (e.g., NaNO₃) that allows ions to migrate between the two half-cells:
Anions (e.g., NO₃⁻) move toward the anode compartment to balance the increasing positive charge.
Cations (e.g., Na⁺) move toward the cathode compartment to replace the positive ions being removed from solution.
This ion flow maintains charge balance in both compartments, allowing electrons to continue flowing through the external circuit (from anode to cathode) and the redox reaction to proceed.
Preventing Charge Buildup and Ensuring Current Flow
If no salt bridge were present:
The solutions would rapidly become polarized (one positive, one negative).
This polarization would generate an internal voltage that opposes the cell’s operation, canceling out the voltage between the electrodes.
As a result, the flow of electrons (current) would stop almost immediately.
Summary Table: Role of the Salt Bridge
Function of Salt Bridge Effect on GalvaOnic Cell peration
Maintains electrical neutrality Prevents charge buildup in half-cells
Completes the internal circuit Allows continuous flow of ions and electrons
Prevents solution mixing Keeps half-cell solutions physically separated
Enables sustained current Allows redox reaction and electricity generation
In essence, the salt bridge is necessary because it prevents charge buildup, maintains electrical neutrality, and completes the circuit, all of which are required for sustained current flow in a galvanic cell.
https://www.perplexity.ai/search/galvanic-cell-why-is-the-salt-HO8UQOLlT2qXNsnKp_yknA
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Chemists are clever folk. It is possible to run the reverse reaction with a positive anode
and a negative cathode on the condition of actually furnishing electrons to the anode.
It is called electrolysis. Diagram below:
DeepSeek:
Could you explain to me how an electrolytic cell works. And could you help me find a site with a visual representation of this type of cell...
An electrolytic cell is an electrochemical device that uses electrical energy to drive a non-spontaneous chemical reaction, a process known as electrolysis. Unlike galvanic (voltaic) cells, which generate electricity from spontaneous reactions, electrolytic cells require an external power source (such as a battery) to force a redox reaction.
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Getting clear on the Galvanic cell set-up:
Galvanic Cell; In the initial set-up, is silver nitrate more attractive to electrons?
Yes! In the initial setup of the galvanic cell, silver nitrate (AgNO_3) is indeed more attractive to electrons. Here's why:
Silver ions (Ag^+) have a higher reduction potential compared to copper ions (Cu^2+). This means they have a stronger tendency to gain electrons and be reduced to solid silver (Ag). Since reduction happens at the cathode, the silver electrode acts as the site where electrons flow toward and where silver ions in the solution get reduced.
On the other hand, the copper anode undergoes oxidation, meaning copper atoms lose electrons and become copper ions (Cu^2+) in the solution. This loss of electrons creates a flow toward the silver electrode, driving the electrochemical reaction forward.
In essence, silver nitrate is more attractive to electrons because its silver ions strongly seek reduction, making the silver electrode the positive terminal of the cell.
Would you like me to clarify any part of this further?
What is the anode: the metal rod or the solution it is in?
The anode in a galvanic cell is the metal rod, not the solution it is in.
The anode is the electrode where oxidation occurs—meaning the metal loses electrons and dissolves into the solution as ions. In your setup with copper, the copper metal rod is the anode. It undergoes oxidation, releasing (𝐶𝑢2^+)ions into the copper nitrate solution while the freed electrons travel through the circuit toward the cathode (silver electrode).
The solution plays an important role in sustaining the reaction, but it is not the anode itself. Instead, it acts as the medium that stabilizes the dissolved ions and allows charge balance to be maintained throughout the cell.
Would you like to go deeper into how the electrolyte influences the reaction?
Same at the cathose: it is the rod and not the solution?
Yes, exactly! At the cathode, the metal rod (the silver electrode, in this case) is the actual cathode, not the solution it’s in.
The cathode is where reduction occurs—meaning ions in the solution gain electrons and deposit as solid metal onto the electrode. In your setup, silver ions (Ag+) in the silver nitrate solution accept electrons and turn into solid silver, which plates onto the silver electrode.
The solution plays a supporting role by supplying the necessary ions, but it's not the cathode itself—the metal electrode is!
You're asking great questions. Want to dive into more details about plating effects or how the process might change with different metals?
What has to get exhausted for the process to stop?
Great question! A galvanic cell stops working when one of the key reactants is depleted. Specifically, these two components must be exhausted for the reaction to stop:
The Anode Material – This is the metal that undergoes oxidation. In a copper-silver galvanic cell, the copper electrode is losing electrons and dissolving into solution as 𝐶𝑢2+. Once all the solid copper is used up, oxidation can no longer occur, halting the flow of electrons.
The Cathode Ions – At the cathode (silver electrode in this case), silver ions (Ag+) in the solution accept electrons and get reduced to solid silver. If all the silver ions are consumed, the reduction process stops, and electrons no longer have anywhere to flow.
Another important factor is the salt bridge—if the electrolyte running through it runs out or dries up, ion flow between the two solutions is blocked, preventing charge balance and stopping the reaction.
Would you like to explore how different cell designs can prolong the reaction?
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