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Principle of the hydrogen pH electrode pHydrunio
pHydrunio is the world's first commercially available platinum hydrogen pH electrode
(patent DE 10 2011 113941). It combines a reversible platinum hydrogen electrode as
a measuring electrode with a platinum hydrogen reference electrode in an internal
buffer as a reference electrode.
The platinum hydrogen electrode is the only electrode whose potential is directly
determined by the hydrogen ion activity. pH value and hydrogen potential are directly
linked. The potential, which depends on the pH value, can be calculated with the help
of Nernst equation.
�� = 0.058 �� @ 20°��
Measuring voltage U and pH value are related to each other as follows:
The pH value can be calculated from the measuring voltage by conversion.
E = Hydrogen potential in Volt
E
0
=Standard Hydrogen potential in Volt = 0,0 V per Definition
.-1
R = 8.314 K mol
K
T = Temperature in K
F = 96485 C mol
-1
p(H
) = Saturated vapour pressure = 1000 hPa
2
a = Activity in mol/l
U = Measuring voltage pH-Electrode in Volt
pH
= 7
inside
��
2
0
�� = ��
�� =
�� = 2.303
�� = − 2.303
�� = 0.059 �� @ 25°��
�� = − 2.303
���� = 7 −
-1
EN - Page 4
+
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2
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��
��
@25°��
0.059 ��
�� = 0.060 �� @ 30°��
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