EXPERIMENT 6: CONDUCTIVITY

    During this experiment, you will test the ability of various substances to conduct electricity.  To do this, you will be using a conductivity apparatus.  The conductivity apparatus will be used to determine whether 1) a solid substance can conduct electricity  2) a pure liquid contains ions  3) a substance dissolved in water is a strong, weak, or non-electrolyte and   4) an ionic solid dissolved in a solvent other than water is a strong, weak, or non-electrolyte.

Obtain a 24-well plate and a conductivity apparatus from the storeroom.

Before starting the experiment, test your conductivity apparatus by touching the two electrodes together to cause the LED to glow.  Make sure that there is a distinct difference from when the light is lit and when it is not.

PART ONE: CONDUCTIVITY OF SOLID SUBSTANCES

1.  Obtain a small sample of each of the solids listed in the first RESULTS box and place them in a row on a clean paper towel.

2.  Touch both electrodes of the conductivity apparatus to one solid at a time.  Note whether or not the LED glows. 

As you can see, the first sample from below is a conductor while the second is not.

3.  Enter all of your observations into the first RESULTS box.

PART TWO: CONDUCTIVITY OF PURE LIQUIDS

1.  This part of the experiment will use the 24-well plate that you obtained form the storeroom.

2.  Place about 40 drops of each of the liquids listed in the second RESULTS box into separate wells of the plate, keeping track of where each liquid is put.

3.  Immerse both electrodes of the conductivity apparatus into one liquid at a time and note whether or not the LED glows.  In this case, the conductivity of the liquid is related to its ion content: if the LED glows, the liquid contains ions; if it does not glow, the liquid does not contain ions to an appreciable extent.

As you can see, the liquid being tested in the first photograph is not conductive and therefore contains a negligible amount on ions.  The liquid in the next picture is conductive and contains ions.

PART THREE:  CONDUCTIVITY OF SOLIDS DISSOLVED IN WATER

1.  Place about 40 drops of each of the solutions listed in the third RESULTS box into separate wells of the 24-well plate, keeping note of which well each solution was put in.

2.  Immerse both electrodes of the conductivity apparatus into each solution one at a time.  For these substances, the LED may glow brightly, faintly or not at all. 

	Here, the LED glows brightly.  The solution is conductive and a strong electrolyte.
	This sample causes the LED to glow faintly.  This solution is semi-conductive and a weak electrolyte.
	When testing this solution, the LED does not glow.  This sample is not a conductor and is a non-electrolyte.

PART FOUR: CONDUCTIVITY OF IONIC SOLIDS DISSOLVED IN NON-AQUEOUS SOLVENTS

The last section of this experiment has been omitted.