Voltaic cell + battery in series

AI Thread Summary
Connecting a battery in series with a voltaic cell can increase the overall potential difference, but it does not inherently increase the rate of redox reactions. The rate of these reactions is primarily influenced by the current flowing through the cell, which can be increased by reducing circuit load resistance. While a higher voltage may enhance the thermodynamics of the process, it can lead to unwanted side reactions, such as water hydrolysis, if the voltage exceeds normal operating ranges. The internal resistance of the battery plays a significant role, and heating the battery can reduce this resistance, potentially increasing reaction rates. Overall, while series connections can enhance voltage, careful consideration is needed to avoid complications from excessive voltage.
Manganese
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Would connecting a battery in series with a voltaic cell accelerate the rate of the redox reaction of the cell?
Hello,
I wanted to know if connecting a battery in series with a voltaic cell would increase the rate of the redox reactions.

Let's take the simplest example of a voltaic cell constituted by a Zn/Zn2+ half-cell connected to a Cu/Cu2+ half-cell. When the circuit is closed, the Zn electrode will get corroded and will dissolve in Zn2+, while the Cu2+ ions in the other half-cell will get reduced to Cu.

What I wanted to know is, if I connect a battery in series with this voltaic cell (maintaining the same current direction), the potential difference should stack (if the Zn/Cu cell has a potential of 1.10 V, connecting a 3V battery in series should bring it to 4.10 V).

Will this potential increase somehow affect the rate of the redox reaction? Or the increase of the potential only affects the thermodynamics of the process (as in, it's just higher voltage) but the kinetics are unaffected? And also, would connecting a battery in series with this type of voltaic cell result in shorting the battery? I know they are getting discharged, but would this be happening at a fast rate or the voltaic cell acts as some sort of resistance?

I drew a sketch
voltaic cell + battery.png
 
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In general - yes, but if the voltage gets too high you can start unwanted side reactions (like water hydrolysis).
 
Manganese said:
I wanted to know if connecting a battery in series with a voltaic cell would increase the rate of the redox reactions.
An "electric battery" is a stack of electrochemical cells, working together, usually in series, to produce a higher voltage than a single cell. In the same sense, a "gun battery" is composed of several guns, that aim to work together.

The rate of the redox reactions can be increased only by increasing the current flowing through the cell. That can be done by reducing the circuit load resistance. That is Ohm's law.

For a fixed load resistance, having more cells in series would increase the current and the rate of reaction. Again, that is Ohm's law.

The circuit resistance includes the internal resistance of the battery. Heating the battery may reduce the battery internal resistance, and so increase the rate of reaction.
 
Manganese said:
Will this potential increase somehow affect the rate of the redox reaction?
Yes, around the 'normal' currents and voltages of the cells used.
But once it's out of the 'normal' range and boiling or electrolysis happens, it may become (very) complicated.
 
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