pH meter

pH meter is a device used for potentiometric pH measurements.

pH can be measured using either pH indicators (like phenolphtaleine) - in form of solution or pH strips - or using potentiometric method. Strips are very useful when all you need is 0.2-0.5 pH unit accuracy. When you need higher precision, pH meter is the only way to go.

In potentiometric methods you measure potential difference between known reference electrode and the measuring pH electrode. Potential of teh pH electrode depends on the activities of hydronium ions. This dependence is described by Nernst equation, thus once the potential has been measured you can calculate the activity. As a first approximation activity is identical to the ions concentration.

pH meter is nothing else but precise voltmeter, connected to the pH electrode, and scaled in such a way that it displays not the measured potential, but ready pH value.

Browse our site to find out more about pH, about pH meter and its history, about pH electrodes and about pH measurements.

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