Calibration liquid for ph

[cheeboonyong]

Hi,

I was wondering if battery water (those used in automobiles) can be used as a neutral 7.0 ph calibration liquid for pH pens. Battery water should be distilled water with almost zero chemicals in it, so ideally should be ph7.0, right?

[whuntley]

Pure distilled water will almost never have a pH of 7.. It has no buffering so the tiniest thing causes big swings. Just coming to equilibrium with the atmospheric CO2 will drop the pH to the low sixes or high fives.

Calibration solutions are solutions of buffers, or mixtures thereof, that are not wildly influenced by contaminants on the probe. Be willing to buy good ones that also give temperature coefficients.

Wright

[cheeboonyong]

Just tested my battery water with my uncalibrated ph pen. showing 6.8...mmm...will buy a qualified calibration liquid to confirm...