Caroline Imreibe

Tornado Reaction

Science Concept: A tornado like reaction will occur when using a mercury chloride solution and a potassium iodine solution. Using a magnetic stirrer and stirring bar, the chemicals will create a tornado like reaction in the flask.

Materials: 1 Liter Erlenmeyer flask filled with 1000 ml of water

10 mL of .01 M Mercury (II) chloride solution (or you may use mercuric nitrate)

20 mL of 2 M Potassium iodide solution

Magnetic stirrer

Magnetic bar

To initial set of a tornado rreaction flask. Start with 800 ml of distilled water and add 10 ml of 0.1 M mercury(II) chloride solution. Slowly add a few mls at a time of 2 M potassium iodide solution. (The solution should turn orange and give an orange precipitate...if you add to much KI too quickly you may miss the orange precipitate.) Continue to add KI until the orange precipitate disappears. Now you are ready to proceed with step 4 below.

Directions:

1.) Gently drop magnetic bar in Flask of water.

2.) Plug in magnetic stirrer and place flask onto stirrer.

3.) If a tornado bottle has already been set up then just continue with the following steps.

4.) Next add approximately 1-2 mL mercury (II) chloride to flask. The orange tornado effect should take place. This step may be repoeated several times.

** Note: If an orange precipitate stays in the solution, then add more KI solution to the flask to turn it back to the original state of a colorless solution.

#We keep the flask for many demonstrations and cycles. This alleviates multiple disposals.

Introduction: Has anyone checked the weather reports today? Well, I heard it was supposed to storm and to be on the watch for a tornado!!!

Explanation: The magnetic bar inside the flask and the magnetic stirrer underneath the flask creates the vortex. The magnetic stirrer works because a motor on the inside is turning an electromagnet. The force is strong enough to spin the magnet on the inside of the glass flask. The fast motion of the solution creates a vortex effect.

When the mercury (II) chloride is mixed with the potassium iodide. A double replacement reaction occurs. The mercury iodide creates an orange precipitate inside the vortex creating a tornado like effect. The precipitate then disappears because it mixes back with the an excess of potassium iodide.

See the reference below for a more complete discussion of the reaction and equilibrium principles involved in this demonstration.

HgCl₂ + KI ---> HgI₂ + KCl

Safety: Handle glassware carefully.

Waste Disposal: See note above#.Ultimately dispose in a mercury waste container and let the water evaporate. Then follow proper final hazardous waste disposal methods.

Reference: Shakhashari, B, Chemical Demonstrations, Vol. 1, U. Wisconsin Press, 1983, p. 271.