Question: the following cell is found to have a potential of...

The following cell is found to have a potential of 0.124 V.

Ag|AgCl (sat’d) || S2- (a = 3.25 × 10-2 M) | membrane electrode for S2-

When the solution of known S2- activity is replaced with an unknown solution, the potential is found to be 0.086 V. What is the pS of this unknown solution and the activity of S2- ion in this unknown solution? Sketch a typical calibration curve for S2- electrode including the theoretical slope.