Experiment 7: Method/Instrumentation

The titration system is comprised of a Radiometer Tri-Burette^TM interfaceed with an PC. The burette is controlled by a titration program written in QBASIC_TM. With this program, one can adjust the size of the addition volumes and obtain potentiometric measurements as the titration progresses. At the end of the titration, the n-tuples: volume added V_ad , E_mV are saved to a file for further calculations.

The Cu-ISE/Reference Electrode Assembly

The potentiometric system is comprised of a solid state Cu-ISE and a double junction reference electrode manufactured by Orion .

E_mv=E_Cu-ISE + kT/n ln[Cu²⁺]

where

E_Cu-ISE: is the potential normal of the Cu-ISE given for [Cu²⁺] = 1M.
k: a constant function of R and F.
T: Temperature in Kelvin.
n: the neumber of electron exchanged

E_Cu-ISE encompasses the reference potential, the correction for departure from ideal behavior (activity coefficients) and various function potential arising from the fabrication of the assembly, it also includes terms coming from activity connection since it is actually the activity of the free Cu²⁺ ion that is probed.

Experimental determination of E_Cu-ISE and (kT)/n

The general requirements are similar than in the previous titration experiment with the glass electrode. See samples