The Essential: pH Meter Calibration

LOS ANGELES - July 12, 2016 - PRLog -- What is a pH meter and what constitutes this device? This type of measuring tool - with digitized versions today - is utilized to test the acidity or alkalinity of a liquid substance such as drinking water, soda, juices and more. These devices provide information on hydrogen-ion activities of liquid substances.

A typical pH meter has a voltmeter attached to a reference electrode and a pH-responsive electrode, facilitating changes and some experimental values. Most of these devices have the pH-responsive electrode made out of glass. The reference electrode meanwhile either is a mercury-mercurous chloride or a silver-silver chloride electrode.

pH meters work like a battery according to Britannica.com. The glass electrode part releases an electrical potential charge which is equivalent to the hydrogen-ion activity in the solution. Normal pH levels are at seven which means, an acidic or an alkalinic solution is expected to have a numeral measure greater or less than the normal pH level. The voltmeter in turn, measures the difference between the glass and the reference electrodes to know the pH level.

These processes all happen inside a digital pH meter and once the tool is measured on a substance, the screen automatically shows a pH level measurement much like that of the function of a thermometer when placed on a human body.

Calibrating the pH Meter

Before using the pH meter, it is important to perform calibration first on the device as with any other measurement tool. Calibration might not be necessary, meaning calibrating the device at all times may not be required but doing so regularly is most recommended. When the device is not calibrated, inaccurate results might show up, i.e. inaccurate measurements to an alkalinic substance after continuously using it with an acidic substance. So how does one calibrate the device?

The Purdue website enumerates steps on how to do it. First, one has to choose the pH mode and set the temperature control feature to 25 degrees Celsius. The cal 2 knob has to be adjusted to read 100 percent. Then, he or she must wash the electrode with deionized water and dry with a tissue such as Kimwipes and Shurwipes, two of some laboratory tissues available.

To begin with, he or she has to set the electrode in the solution level of pH 7 buffer which is the neutralized measure, allow the display to be stable and set the display to cal 1 to read pH 7. Then, remove the electrode from the buffer, the website added.

Once more, wash the electrode with deionized water and dry using tissue paper. Then, the next phase involves adjusting the solution electrode of Ph 2 buffer, allow it to get stable and set the display to read 2 through adjusting it at cal 2. Finally, remove the electrode from the buffer as the website suggested. The same washing process follows, rinsing the electrode with deionize water and wiping dry with tissue.

Sources:

http://chemed.chem.purdue.edu/genchem/lab/equipment/phmet...

http://www.britannica.com/technology/pH-meter