This morning's science club demonstrations.

As was promised here are the directions for two of this morning's Science Club demonstrations:

(1) Nitrogen triiodide explosion: This one is very simple and involves mixing two chemicals together. What is needed is (a) at least 10 grams of elemental iodine crystals, (b) 25 mL of ammonium hydroxide, 28% solution (CAUTION: ammonium hydroxide solution is caustic and poisonous if swallowed, it has a highly disagreeable odor, and can cause severe burns to the skin and eyes. Use only with very good ventilation (e.g. out doors). If skin contact occurs wash with plenty of running water; if eye contact occurs wash for at least 15 minutes with running water and contact a physician.), (c) a small (1 - 2 fl.oz.), clean bottle with a tight-fitting plastic cap and (d) a stainless steel spatula.

Using the spatula carefully transfer the iodine crystals into the clean bottle and immediately add the 25 mL of ammonium hydroxide. Cap the bottle and shake for about 30 seconds. Set the bottle aside for about 1 hour then you're ready to give it a shot!

To cause the nitrogen iodide to explode simply use the spatula to remove a small amount of the brown material from the bottom of the bottle and smear it onto a paper towel or newspaper and allow it to dry in the air. Once it is completely dry any disturbance to the material will cause and endothermic explosion. Another application is to smear the material onto a sidewalk or driveway.

Any stains that result from residual iodine can be easily removed with a few crystals of sodium thiosulfate, wetted with water and worked into the stain. The same will remove any iodine stains from clothing or skin.

For long-term storage be sure to keep the brown material in the bottle always covered with liquid. It is safe when wet. Once the initial reaction, in the bottle, has occurred, about half of the liquid can be discarded (down the drain is okay) and the bottle refilled with ordinary tap water. This will lessen the odor impact of the ammonia when opening the storage bottle.

(2) Sodium acetate crystal tower: You will need: (a) 160 grams of sodium acetate trihydrate, (b) 100 mL of pure water , (c) a 400 mL glass beaker or another suitable PYREX container with a pouring spout, (d) a 250 mL Erlenmeyer flask, (e) a #6 solid rubber stopper, and, if needed, (f) a lab balance for accurately weighing the sodium acetete, and (g) a 50 mL graduated cylinder for accurately measuring the water. In addition, for the purposes of heating the solution to a microwave oven, set to high, will work well. (CAUTION: Use proper precautions for handling very hot containers!)

Place the 160 grams of sodium acetate (be sure to save back a couple of crystals for later use) into the beaker and add exactly 30 mL of water to the beaker. Place the beaker in the microwave oven and heat it until all the solid sodium acetate is dissolved. There can be no undissolved crystals, or the solution will quickly crystalize before you can do the demonstration. While the solution is heating take about half of the remaining pure water and rinse the Erlenmeyer flask and drain it, but do not dry it. Also rinse the rubber stopper and place it in the mouth of the flask.

After the solution has been made, and there are no undissolved crystals on the bottom of the beaker, carefully pour the hot solution into the flask. At this point is is very important that the solution is gently poured into the flask such that none of the solution is poured down the inside of the flask wall. Be a gentle as possible to prevent splashing of the solution inside the flask and to prevent bubbles from being formed as the solution is poured. When the solution has been poured into the flask carefully insert the rubber stopper and set the flask aside to cool. DO NOT SHAKE the flask!

Place the crystals you save back in the middle a shallow dish or dessert plate. Once the solution has cooled to room temperature unstopper the flask and carefully and slowly pour the solution onto the crystals. You will notice that when the solution first hits the plate it will solidify and spread out a little. Keep pouring, slowly, and watch the tower of crystal grow upward. be careful to not allow the growing tower of crystals to touch the lip of the flask otherwise the solution remaining inside the flask will quickly crystallize.

The crystal tower is safe to touch, but be careful that there may be some hot spots on its interior. When finished you can put the crystals back into the beaker and start all over. Only this time there is no need to add any more water, just reheat in the microwave to fully liquify.