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cheap pH meter vs pH paper ?

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cker

cker

Rising Star
A FOAF owns a cheap pH meter to measure pHs in the 12.5 range. The problem is, the pH meter doesn't agree with color changing pH paper. To get to 12.5, the pH paper says much more lye is needed than the pH meter says. My FOAF doesn't trust the pH meter but it's very nice to see a number and know the correct pH is achieved.

This pH meter appears to function (water measures close to 7 while adding base raises the reading). Does anyone have any knowledge about these devices? How do other FOAFs set the pH of solutions? Perhaps the pH paper is good enough and more reliable? TIA...
 
You should get the pH calibration buffer solutions. The standard is two solutions of pH 4.01 and pH 7.01. My checker has two screws that you have to turn until it exactly reads the pH of the solution you are measuring (4.01 or 7.01).
 
I find pH papers to be fine. The chemistry discussed on these boards doesn't really require the measurements to be all that accurate and I found cheap pH meters to be nothing more than a pain.
 
1. Calibrate your pH meter
2. Use narrow range pH papers

1-14 papers cen be way too deceiving, especially if you are experimenting and not following a TEK.
 
I'll look into calibration and play around with the meter a bit but I'll also get some narrow range pH papers. I had been using 0-13 paper. Thanks for the suggestions.
 
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