An ammonium ion selective electrode responds to both NH4+ and H+, but not to NH3. (pKa=9.244 for NH4+)
A) What pH conditions must be imposed to ensure the electode properly represents toe activity of NH4+
B) Why is the ionic strength an important factor when using this or any ISE? How can you compensate for this effect?
C) Using the Formula EISE = constant + RT/nF ln(ai +ki,jaj), what are the TWO pH conditions that present 10% error on a measurement of 1.00 x10-4M NH4+, if kNH4+ H+ = 0.035? You may assume identical activity coefficients
This solution answers 3 electrode chemistry questions, addressing pH conditions, ionic strength, ISE and EISE