/sci/ - Science & Math » Thread #12272912

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Anonymous Sun 25 Oct 21:19:40 2020 No.12272912 View Reply Original Report

Quoted By: >>12272987 >>12273006 >>12273264

explain to a brainlet how ph aka H+ ions influences the voltage of a potentiometer

Anonymous

Anonymous Sun 25 Oct 2020 21:39:29 No.12272987 Report

Quoted By: >>12273025

>>12272912
the solution may be still, but inside is a wave pool of fluctuation compressions and expansions of charge densities, like crests on a wave, charges crest into dipole moments, sometimes enough to induce a current as a battery may in your potentiometer.

Anonymous

Anonymous Sun 25 Oct 2020 21:44:35 No.12273006 Report

Quoted By: >>12273025

>>12272912
shifts equilibrium iirc, and the change in concentrations causes change in conductivity aka resistance

Anonymous

Anonymous Sun 25 Oct 2020 21:49:41 No.12273025 Report

Quoted By: >>12273037 >>12273161

>>12273006
>>12272987
what even

Anonymous

Anonymous Sun 25 Oct 2020 21:52:48 No.12273037 Report

Quoted By: >>12273045

>>12273025
google "wheatstone bridge"

Anonymous

Anonymous Sun 25 Oct 2020 21:54:49 No.12273045 Report

Quoted By: >>12273052

>>12273037
I KNOW what a wheatstone bridge is and I don't think that is of use here

my question is: how the hell does the pH change the voltage that we measure with a electrode

Anonymous

Anonymous Sun 25 Oct 2020 21:57:27 No.12273052 Report

Quoted By: >>12273067

>>12273045
Voltage is simply electric potential difference and if you have a buildup of potential in one electrode through buildup of H+ ions, you can expect the measurement for potential energy difference between one electrode and the other to be higher.

Anonymous

Anonymous Sun 25 Oct 2020 22:00:54 No.12273067 Report

Quoted By:

>>12273052
you do not (((actually))) measure the voltage, you measure the changing cell voltage difference but why does the proton influence the cell voltage if the cell only needs silver and silverchloride to build be a valid cell??

Anonymous

Anonymous Sun 25 Oct 2020 22:24:05 No.12273161 Report

Quoted By:

>>12273025
hmm, every molecule in the solution is a staticy balloon, what happens if touch balloon? zap zap.

adding H+ is like rubbing some balloons with wooley feet, more static per molecule, when they touch potentio meter they go zap zap and it moves

Anonymous

Anonymous Sun 25 Oct 2020 23:06:46 No.12273264 Report

Quoted By:

>>12272912
H+ diffuse across membranes according to chemical and electrical potentials. Equilibrium is when enough H+ have crossed to balance the remaining chemical potential against the electric potential they've created.
Measuring that electric potential tells you the chemical potential which is converted to pH.

Anonymous

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Anonymous Mon 26 Oct 2020 00:04:12 No.12273461 Report

Quoted By: >>12273475 >>12273481

https://en.wikipedia.org/wiki/PH_meter#Design_and_use
it's basically turning the glass globe into a very small capacitor

Anonymous

Anonymous Mon 26 Oct 2020 00:09:02 No.12273475 Report

Quoted By:

>>12273461
although, it's not actually used as a capacitor, it's used to generate a voltage potential that's detectable as a difference in voltage between the two electrodes. but the way it's shaped and separates charges is sorta like a capacitor

Anonymous

Anonymous Mon 26 Oct 2020 00:10:45 No.12273481 Report

Quoted By: >>12273489 >>12273493

>>12273461
still makes no sense, the protons replace the positively charged ions in the glass, but what IS changing the voltage? why shouldnt the water just act as a salt bridge to connect both electrode? the ph on the outside shouldnt effect the ph on the inside, no??

Anonymous

Anonymous Mon 26 Oct 2020 00:13:53 No.12273489 Report

Quoted By: >>12273493

>>12273481
>but what IS changing the voltage?
the gradient across the glass bulb is.

>why shouldnt the water just act as a salt bridge to connect both electrode?
it does, that's how the whole probe works. the gradient that's established across the globe acts like a tiny voltage source that changes what would otherwise be a known voltage across the two electrodes. you amplify any voltage difference in the circuit formed by the solution across the two electrodes.

Anonymous

Anonymous Mon 26 Oct 2020 00:14:52 No.12273493 Report

Quoted By:

>>12273481
>>12273489
>On immersion of the glass electrode and the reference electrode in the test solution, an electrical circuit is completed, in which there is a potential difference created and detected by the voltmeter. The circuit can be thought of as going from the conductive element of the reference electrode to the surrounding potassium-chloride solution, through the ceramic membrane to the test solution, the hydrogen-ion-selective glass of the glass electrode, to the solution inside the glass electrode, to the silver of the glass electrode, and finally the voltmeter of the display device.[9] The voltage varies from test solution to test solution depending on the potential difference created by the difference in hydrogen-ion concentrations on each side of the glass membrane between the test solution and the solution inside the glass electrode.
this paragraph explains it

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