Eli5 How do heat patches work and how do they stay hot for so long?
In: Chemistry
I’m assuming you mean chemical ones, and not electrical, given the tag is “Chemistry”.
It’s essentially analogous to a fire. A few chemicals combine in a way that reduces their total energy (sort of like how a ball will fall to earth to reduce its gravitational potential energy).
The potential energy the chemicals had before is turned into particle wiggles (sort of like how a ball falling to earth starts bouncing and making sound). Temperature is basically just a measure of how wiggly a substances particles are, so the energy converting into wiggling generates heat.
This is basically how a fire burns. It takes two chemicals that have high potential energy (oxygen and a hydrocarbon) and convert them to chemicals with lower energy, turning the excess energy into particle wiggling, aka heat.
Chemical heat patches keep their heat for long periods of time the same way a fire does. It just keeps converting chemicals to keep producing heat.
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