Question

A pH electrode obeys Nernst equation and is being operated at 25°C. The change in the open circuit voltage in millivolts across the electrode for a pH change from 6 to 8 is

• A. 118.4

Answer 1

The correct option is A 118.4
Sensitivity of an ideal pH probe is, 59.2 mV/pH and pH is changing from 6 to 8
= 8 - 6 = 2

$\therefore$ Output change of pH probe
$=59.2\times 2=118.4mV$