How can we test a reference electrode?

Document ID

Document ID TE12425

Published Date

Published Date 08/06/2020
Question
How can we test a reference electrode?
Summary
To check a reference electrode, it is possible to use a single pH electrode and then measure the potential in different pH buffers. The pH electrode must be in good shape.
Answer
A possibility is to use a single pH electrode and then measure the potential in different pH buffers. The pH electrode must be in good shape.
 
For example, if you need to test a XR300 (B20B300) Ag/AgCl reference electrode filled with KCl 3M AgCl Saturated, a pH of 7 is expected to have potential reading of 0 mV. Using a theoretical slope, the expected mV reading can be calculated. as shown below: 
 
At pH 1.09         (7.00-1.09) x 59.16 = 349.6 mV
At pH 4.005       (7.00-4.005) x 59.16 = 177.2 mV
At pH 7.00         (7.00-7.00) x 59.16 = 0 mV                                    
At pH 10.012     (7.00-10.012) x 59.16 = - 178.2 mV
 
59.16 mV /decade is the slope at 25°C. The slope is 58.16 mV /decade at 20°C
 

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