These heat pads are highly cool to watch . If you would wish to see the cognitive process and have the fourth dimension , you candownload this 1.2 - megabyte MPEG fileand see it happen . bend the metallic element disc starts thecrystallizationprocess , and you’re able to see the crystallization proceed through the liquid .
What is happening here is strange , but the process can be understood if you think about water freezing . Water block at 32 degrees Fahrenheit ( 0 degrees light speed ) . If you were to bind athermometerin a loving cup of water and put the loving cup in the freezer , you would discover that the temperature of the piddle fall to 32 degrees F and then hangs there until all of the weewee is completely frozen . Then the temperature of the solid H2O fall to the temperature of the freezer .
What if you could somehowsupercoolthe piddle ? That is , say that you could get the piss ’s temperature to 10 degree below the freezing head without it crystallizing into a solid – you could sometimes do this using a very clean glass and distilled water so there are no point for the water to lead off crystallizing . In this condition , if you tip the trash the temperature of the water will jump up to 32 academic degree F ( 0 degrees C ) , and the water will solidify rapidly .
A heating plant gang like the one you are delineate containssodium acetateand pee . It turns out that sodium acetate rayon is very proficient at supercooling . It " freezes " at 130 degrees F ( 54 degrees C ) , but it is well-chosen to live as a liquid at a much lower temperature and is extremely stable . get across the disk , however , has the power to pressure a few molecule to sky to the solid country , and the relief of the liquid state then rushes to solidify as well . The temperature of the solidify liquid jumps up to 130 degree F in the process .
When youboilthe solid , you melt it back to the liquid state . You have to completely dissolve every quartz glass , by the way , or the liquid will quickly re - solidify . you’re able to double this wheel constantly , theoretically , just as you’re able to freeze and dissolve body of water as many times as you care . The plastic sack eventually wears out and leaks , though ( since sodium acetate rayon is a food linear , it is non - toxic ) .
