I’m still sick, in fact, it’s gotten much worse since Saturday. All I could do today was sleep, go to the doctor to get a note for work, and then peruse the brand new Netflix subscription on the couch together with the cat.
So… I finally watched Frozen, which everybody was going on about last year. It was nothing more, nothing less than what I’d expect from a Disney film of this sort, but the singing was nice, and the instant ice was pretty cool.
Speaking of instant ice, that’s actually achievable without magic, and is readily available in the form of a chemical reaction in instant cold packs. The results may not be as flashy as a giant castle on a mountaintop, but they work well for first aid applications.
The chemical reaction in instant cold packs is endothermic – it absorbs heat, as opposed to the instant heat packs that create it. A chemical cold pack is a bag of water that contains a tube filled with ammonium nitrate – a white crystalline powder that dissolves in water. When the bag is squeezed, the inner tube breaks and the powder mixes with the water, causing the reaction. Water molecules split the nitrate ions from ammonium ions, and this separation uses so much energy that heat gets absorbed, and the temperature of the whole bag lowers, staying cold for at least an hour.
You can watch below what an endothermic reaction between two solids looks like while I go to bed and hope not to cough up half a lung tonight.