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  5. Demo 26: Conductivity of Solutions

Conductivity

Part 1

Solutions to use:

  • Water
  • Salt Water
  • Sugar Water
  • Soap Water
  • Strong acids
  • Weak acids
  • Strong bases
  • Weak bases

       

Procedure

Plug in the conductivity aparatus and switch the incandescent light bulb on.  Putting the probe in one of the solutions will cause the light bulb to light if there is conductivity.  Caution: do not touch the leads of the probe because of shock hazard.

       

Part 2

Procedure

This procedure uses a titration set-up along with the conductivity meter to show the precipatation of Barium Sulfate from solution.  Barium Sulfate is non-conductive, while Barium hydroxide and Sulfuric Acid both conduct electicity.

Measure 25 mL of 0.2M Barium Hydroxide and put it in a 400 mL beaker along with enough DI water to fill the beaker about one third full.  Place the beaker on a magnetic stir plate and stir the contents slowly.  Put the Conductivity probe in the beaker along with a pH electrode.  Using a Buret with 0.2M Sulfuric Acid titrate the Barium Hydroxide.

Starting about 23 mL of Sulfuric Acid used, the light bulb should start to dim.  (Make sure you go very slowly near the equivelance point since the ratio may not be exactly 1:1 (because of precipitation of barium hydroxide in the solution bottle)).  If you are careful and go drop by drop at the end you can get the light bulb to go out.  Excess Sulfuric Acid will cause the bulb to light up again.