chemistry help - fuel cells

Hello, I'm stuck on question 5eii on this pmt sheet - https://www.physicsandmathstutor.com/pdf-pages/?pdf=https%3A%2F%2Fpmt.physicsandmathstutor.com%2Fdownload%2FChemistry%2FA-level%2FTopic-Qs%2FAQA%2FPhysical-II%2F1.11-Electrode-Potentials-and-Electrochemical-Cells%2FSet-F%2FElectrode%20Potentials%20%26%20Cells%203%20QP.pdf
- Also why certain cells cannot be recharged.

ms - https://www.physicsandmathstutor.com/pdf-pages/?pdf=https%3A%2F%2Fpmt.physicsandmathstutor.com%2Fdownload%2FChemistry%2FA-level%2FTopic-Qs%2FAQA%2FPhysical-II%2F1.11-Electrode-Potentials-and-Electrochemical-Cells%2FSet-F%2FElectrode%20Potentials%20%26%20Cells%203%20MS.pdf
I'm just confused about where they managed to get the equation from. In general, where can I learn more about fuel cells and rechargeable cells? chemguide doesn't have any notes on it

Reply 1

Nitrotoluene

Original post by mitostudent

Hello, I'm stuck on question 5eii on this pmt sheet - https://www.physicsandmathstutor.com/pdf-pages/?pdf=https%3A%2F%2Fpmt.physicsandmathstutor.com%2Fdownload%2FChemistry%2FA-level%2FTopic-Qs%2FAQA%2FPhysical-II%2F1.11-Electrode-Potentials-and-Electrochemical-Cells%2FSet-F%2FElectrode%20Potentials%20%26%20Cells%203%20QP.pdf
- Also why certain cells cannot be recharged.
ms - https://www.physicsandmathstutor.com/pdf-pages/?pdf=https%3A%2F%2Fpmt.physicsandmathstutor.com%2Fdownload%2FChemistry%2FA-level%2FTopic-Qs%2FAQA%2FPhysical-II%2F1.11-Electrode-Potentials-and-Electrochemical-Cells%2FSet-F%2FElectrode%20Potentials%20%26%20Cells%203%20MS.pdf
I'm just confused about where they managed to get the equation from. In general, where can I learn more about fuel cells and rechargeable cells? chemguide doesn't have any notes on it

Hello mitostudent!

5eii:
You can represent the overall reaction as follows:

PbO2 + Pb + 2 H2SO4 <==> 2 PbSO4 + 2 H2O

The equation above shows the conversion of lead dioxide and lead back into lead sulfate and water during the recharging of the lead-acid battery.

Quote
Also why certain cells cannot be recharged.

Unquote
Some cells cannot recharge due to irreversible chemical reactions.

NOTE: I don't understand your second question. Can you be more specific?

Krgds,
Sandro
Italy Flag.png

(edited 9 months ago)

Reply 2

mitostudent

Original post by Nitrotoluene

Hello mitostudent!
5eii:
You can represent the overall reaction as follows:

PbO2 + Pb + 2 H2SO4 <==> 2 PbSO4 + 2 H2O

The equation above shows the conversion of lead dioxide and lead back into lead sulfate and water during the recharging of the lead-acid battery.
Quote
Also why certain cells cannot be recharged.
Unquote
Some cells cannot recharge due to irreversible chemical reactions.
NOTE: I don't understand your second question. Can you be more specific?
Krgds,
Sandro
Italy Flag.png

Hello, I'm a little confused as to how certain reactions are said to be reversible and those that are not, I thought in the electrochemical series all of the equations were reversible?
Also, my other question was about resources for fuel cells, as I haven't found many that explain the rechargeable cells in full
Thanks for your response 🙂

Reply 3

Nitrotoluene

Original post by mitostudent

Electrochemical series data presents standard reduction potentials for half-reactions, not actual electrochemical processes.
Reversible reactions occur in both forward and reverse directions, with identical rate constants.
You can control the direction of these reactions by adjusting the electrode potential, reactant or product concentrations.
Changing the voltage applied to the electrode means altering the voltage.
By adjusting the voltage, you can influence the reaction at the electrode surface.
By actively adjusting the voltage, you can switch the reaction's direction from the oxidation of zinc and reduction of copper(II) ions (Zn + Cu^2+ <==> Zn^2+ + Cu) to the reduction of zinc ions and oxidation of copper (Zn^2+ + Cu <==> Zn + Cu^2+).
Irreversible reactions proceed in only one direction, and changing the conditions does not enable their reversal.
These reactions typically face a substantial activation energy barrier, making their reversal difficult or impossible.

For example, the reaction between chlorine and water (Cl2 + H2O ==> 2 HCl + O2) is irreversible due to the high activation energy required to reverse the reaction.
_________________________________________________________________________________________
Rechargeable Fuel Cells
There are several resources that provide information on rechargeable fuel cells, including:
The Fuel Cell and Hydrogen Energy Association (FCHEA)
The National Renewable Energy Laboratory (NREL)
The Department of Energy (DOE)
The International Association for Hydrogen Energy (IAHE)
The Journal of Power Sources
The Fuel Cells Bulletin

Try Googling them.

Bye,
Sandro

(edited 9 months ago)