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Topic: Calibrating PH meter  (Read 840 times)

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Offline Dynamin

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Calibrating PH meter
« on: January 30, 2019, 02:43:16 PM »
I'm having a b$*%( of a time calibrating my PH meter with those 3 solutions.
I was wondering, would it not be easier to just calibrate my meter by sticking it in some white vinegar, since that is always a 2.4 PH??

Thank in advance

Offline chenbeier

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Re: Calibrating PH meter
« Reply #1 on: January 30, 2019, 03:22:27 PM »
This would be not very accurate. Vinigear is naturla product and amounz of acetic acid differs. Zou need a curve not only one point. You have to to know in which range you have to measure.

Acidic solution: calibrate with pH 7 and pH 4  or lower.
alcaline solution: take pH7 and pH 10 or higher.

Offline Borek

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Re: Calibrating PH meter
« Reply #2 on: January 30, 2019, 07:10:44 PM »
white vinegar, since that is always a 2.4 PH??

It is not.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Offline Dynamin

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Re: Calibrating PH meter
« Reply #3 on: February 02, 2019, 03:32:51 PM »
Okay, so I finally have the darn thing calibrated properly.  Now I'[ve got another problem.
I've made a topical solution containing vitamins, minerals and amino acids.  Whenever I buffer it to PH7, and I then leave it at RT for a few days, the PH is somehow magically gone up to 7.5 or 8.0.

How can that be??

It cant be the PH meter because whenever I test it on the calibration fluid its spot on

Offline billnotgatez

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Re: Calibrating PH meter
« Reply #4 on: February 03, 2019, 02:21:41 PM »
Carbon dioxide?

Offline Dynamin

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Re: Calibrating PH meter
« Reply #5 on: February 03, 2019, 02:32:07 PM »
Carbon dioxide?
CO2 would make the PH go down, not up. Would it not??

I think it might be going up because I have quite a bit of undissolved solids in the solution.
So I guess my next step should be to microfilter them all out

Offline billnotgatez

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Re: Calibrating PH meter
« Reply #6 on: February 03, 2019, 02:44:49 PM »
I apologize
I misread your post.
You are correct - Aqueous carbon dioxide reacts with water forming carbonic acid.

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