You are using a glass-membrane pH electrode to determine the pH of an unknown solution. You prepare two calibration standards with a pH of 4.006 and 7.000. These solutions result in electrode potential measurements of 0.395 and 0.224 V, respectively, at 25°C.
a. Calculate both the slope of the calibration and the electrode's value.
b. If your unknown produces an electrode potential of 0.300 V, what is the unknown solution's pH?
c. What are the 5 most significant errors that occur with the use of a pH electrode?
d. Write an equation, equivalent to the pH electrode equation, for an electrode that is selective for sulfate. You can assume that T=25°C, and you do have to account for the fact that sulfate has a 2- charge.