Chem 152 Lab 5

These are the components you will use to assemble the half-cells you will in ths lab.  Shown are the Zn and Cu metal electrodes (Pb and Ag are not pictured).  A piece of cellulose film (taken from the spool) will be placed on the end of the glass tube and secured with the rubber band.  On the far right is the Ag/AgCl reference electrode, which will be provided pre-assembled for the lab.

Carefully place a square piece of cellulose film over the polished end of the glass tube (the smoother of the two ends - the rougher one can tear the film).

Secure the cellulose on the end of the tube by sliding the rubber band over the film-covered tube end, being careful not to rip the film.

Make sure the film is stretched tightly and is wrinkle-free, to prevent leaks and provide a reliable porous membrane for the "salt bridge".  Use DI water to test for leaks prior to adding any metal-ion solution in the final assembly steps.

To each of the assembled tubes, place a metal-ion solution and the corresponding metal electrode such that the metal is in contact with the solution, but also so that the metal is not touching the cellulose film.  The assembled Cu electrode and the Ag/AgCl reference electrode are shown here.

Place the assembled half-cells and the reference electrode in a specimen jar and add potassium nitrate so that the bottoms of the electrodes are immersed in it.  The potassium nitrate solution is providing the last component necessary for the "salt bridge".  The Fluke metere is shown here with the leads attached to the Ag/AgCl reference electrode and the Cu electrode, both of which have been temporarily placed in an empty beaker.