explodes at 350 °C
|Lead Azide||molecular mass
Lead azide is a common primary explosive used as a standard to compare sensitivity among other primary explosives. Making lead azide is not a simple task, this laboratory uses advanced techniques and equipment. Getting the chemicals will be another task. Sodium azide is an unstable, therefore regulated, material nearly impossible to get, it will need to be synthesized. Lead azide is sensitive to heat, shock and friction. The addition of dextrin to this lab prevents the formation of large crystals which can be very dangerous.
|lead nitrate||Buchner funnel|
|sodium azide||graduated cylinder|
Dissolve 2.33 g of sodium azide and 0.058 g of sodium hydroxide in 70 mL of water by shaking in a separatory funnel. This is solution A. Dissolve 6.9 g of lead nitrate and 0.35 g of dextrin in 90 mL water in a 250-mL beaker, add 1 or 2 drops of 10% sodium hydroxide to bring the pH to about 5. This is solution B. Heat solution B to 60-65° on a water bath and agitate it with a plastic or hardwood stirring rod. The stirring should be as efficient as possible to prevent the formation of large crystals. Stirring, while vigorous, should not produce any spattering of the mixture and the stirring should not rub against the walls of the beaker. The friction might cause some crystals to explode. Add solution A dropwise to solution B while stirring. The addition should take about 10 minutes. Remove the beaker from the water bath and continue stirring the mixture in the beaker while cooling to room temperature, this will take about 1 hour. Allow the precipitate of lead azide to settle and pour the solution over a filter to collect the crystals. Use suction filtration with a Buchner funnel if possible. Add 150 mL of water to the crystals to wash them, add the water in 50 mL increments. Dry the sample for 8-15 hours or longer, but no more than 24, at 65 °C. The lead azide should form small spherical crystals that are opaque in color. The yield should be around 5 g. Store the lead azide moist in a rubber stoppered plastic bottle if you must. If you do not have a separatory funnel for solution A, use a beaker to prepare the solution and a pipet or buret to to add it to solution B. You will need a graduated cylinder for measuring liquids, and a thermometer to monitor the temperature.
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