Does the ph of distilled water vary much ? Can otc distilled water be used to make diy ph calibration solution ?Ubya - 31-3-2019 at 09:47
even distilled water as CO2 dissolved, so its pH is slightly acidic, and can not be ignored. no you can't use distilled water as a calibration source,
it would be too easy UC235 - 31-3-2019 at 09:54
pH of the distilled water means almost nothing since it has no ionic strength and can't be accurately read by a pH meter. Once the buffer salts are
added, they will dominate the pH. However, it is good practice to boil water used to make solutions to expel CO2 and store in tightly sealed
containers.Ubya - 31-3-2019 at 10:15
i thought he meant just plain distilled water as the calibration solitution, without a bufferdraculic acid69 - 31-3-2019 at 10:38
I seen one guy use skim milk as a calibration standard apparently it is ph6 exactly.CharlieA - 31-3-2019 at 17:00
The pH of pure water is 7, by definition, because the [H+] = 1 x E-7M. Granted that the ionic strength of pure water is very low, I would think that
a decent pH meter would read 7 for a sample of pure water. Certainly to achieve a decent, reliable calibration the use of 1 or more buffer solutions
is well-advised.Harristotle - 1-4-2019 at 05:43
potassium hydrogen tartrate is a NIST primary pH standard.
Buy yourself some cream of tartar, mix it with distilled or rainwater and use a saturated solution as a pH 3.557 at 25 °C
Cheap !
[Edited on 1-4-2019 by Harristotle]itsafineday - 1-4-2019 at 05:54
I would think that a decent pH meter would read 7 for a sample of pure water.
I wouldn't.
If you look at this https://en.wikipedia.org/wiki/Glass_electrode#Construction
there's picture of a pH electrode, and the bit numbered 7 is the problem
It's a "salt bridge" and it will leak buffer from the probe into the water you are trying to measure.
