申論題

15. (7%) (a) Describe the source of pH-dependence in a glass membrane electrode. (b) The cell 
 has a potential of 0.2094 V when the solution in the right-hand compartment is a buffer of pH 4.006. The following potential is obtained when the buffer is replaced with an unknown solution: -0.2910 V. Calculate the pH and the hydrogen ion activity of the unknown solution.