Supplying the science hobbyist, industry, government, schools & universities since 1998.
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demonstrates an endothermic reaction.
1. Place approximately 100 mL of water in a large beaker or glass jar and record the temperature.
2. Quickly dump in 15 grams of Ammonium Nitrate and stir.
3. Note the temperature change as the Ammonium Nitrate dissolves.
The drop in temperature will be surprising and will continue to decrease for several minutes. Frequently the solution gets so cold that water vapor from the air begins to condense on the outside of the beaker.
Small zip-lock baggies of Ammonium Nitrate can be kept handy as cold packs. When needed, simply add water in any form and seal the bag for an instant cold pack.