Timeline for Experiment on pH vs Rate of Electrolysis - what do the results actually say?
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
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| Oct 29 at 20:54 | comment | added | PAEP | I think you are talking about faradaic resistance. The faradaic resistantance is related to the velocity of the the redox reactions on the electrodes. Since you are working with a constant potential, this is related to the concentration of reactants ($\ce{H^+, OH^-, ...}$). Check the Tafel equation and kinetic of redox electrode reactions. | |
| May 31 at 18:47 | comment | added | Eshwar Kolli | The voltage is held constant, the resistance of the solution changes with pH - that is essentially what im trying to find as resistance is inversely proportional to both the current and rate of gas production | |
| May 31 at 14:01 | comment | added | Noah | I think you're missing the point I was making. I am not talking about the ionic resistance if no ions are present. I am talking about "concentration polarization" since there is basically no reagent present to do hydrogen evolution from protons or oxygen evolution from hydroxide you will need to do these from water. If we look at the potential required for either reaction from water we find a cell potential beyond the thermodynamic potential (1.23V) but a cell potential of around 2V. So you lose 800 mV just because of the pH (concentration of reagents), not the ionic conductivity. | |
| May 31 at 13:54 | comment | added | Maurice | Of course at pH new 7, the amount of $\ce{H+}$ and $\ce{OH-}$ is extremely low. But it is not important for electrolysis if the solution contains high amounts of ions having no effect on pH. For example, a solution of $\ce{Na2SO4}$ may be neutral and be electrolyzed without difficulty. | |
| May 31 at 13:48 | comment | added | Noah | pH is a really important factor for water electrolysis. He applied a constant voltage over a cell, when near pH 7 the amount of OH- or H+ is ridiculously low. This means the hydrogen evolution or oxygen evolution reaction will use water as the reagent for a significant amount of current. This changes the required cell potential from 1.23V to around 2V. You basically lose 800 mV to concentration polarization. | |
| May 31 at 12:05 | history | answered | Maurice | CC BY-SA 4.0 |