The measurement of pH using a glass electrode obeys the Nernst equation. The typical response of a pH meter at 25.00oC is given by the equation ϐmeas = ϐ ref 1 0.05916 pH where ϐref contains the potential of the reference electrode and all other potentials that arise in the cell that are not related to the hydrogen ion concentration. Assume that ϐref = 0.250 V and that ϐmeas = 0.480 V.
a. What is the uncertainty in the values of pH and [H+] if the uncertainty in the measured potential is 61 mV (60.001 V)?
b. To what accuracy must the potential be measured for the uncertainty in pH to be 60.02 pH unit?

  • CreatedMay 05, 2015
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