Hello and welcome to Physical Chemistry Laboratory. Today's topic, Electric Conductivity. We want to measure the conductivity of an electrolytic solution. In this experiment, the conductivities of the weak electrolyte acetic acid

and the strong electrolyte sodium chloride are measured at six different concentrations each. First of all, dilution series of both electrolytes have to be prepared using one molar stock solutions.

Care should be taken to always use a clean and dry pipette for each solution preparation. To get reproducible results, the volumetric flasks always have to be filled exactly up to their graduation marking with distilled water. Do not mix up the stoppers of the flasks.

The dilution process has to be carried out exactly in the order given in the handout. During the preparation of the samples, CO2 from the air will inevitably dissolve in the solution. This systematic error can be taken into account for by measuring a so-called blank value. When doing the measurement with a conductometer,

its electrode first has to be rinsed by the sample to be measured. Fill the solution to be measured into a small beaker, immerse the electrode into the solution, give it a brief stir, and discard the sample. Fill up the beaker again and now do the actual measurement.

When changing from acetic acid to sodium chloride, rinse the electrode repeatedly with distilled water until the conductometer indicates the original conductivity of the blank sample. Repeat the procedure twice for every solution.

More information about the experiment, and especially its evaluation, can be found in the textbook and in the handout. Good luck in the lab and thanks for watching.