Quote:
Originally Posted by masque de Z
Has anyone here tried to test this "claim" ? I mean give me a break i tried this evening to freeze faucet water and it took 160-164 min (obviously i couldnt be opening freezer all the time so i am guessing a bit earlier than i opened it last based on the time of the prior test and the condition of the ice that had started to form from the perimeter of the can first to full disk eventually to build 2 mm thick ice wall at the top (water below ) (so lets define this as the reference). I use a metal cylindrical can of 500ml volume probably filled to about 450 ml. Then used boiled water when down to around 60C still steaming and put it in the same location in the freezer same can same volume and got the same type of thickness fully formed solid top surface of 2mm at about 170-174min ie about 10 min later. Guess what, i bet that extra 10 min is the time it takes for 60 to drop to 15-20 that faucet water is, lol.
So there you have it do it yourselves, my setup is ridiculously crude but faithfully done with as good conditions as possible and i got the hot water to freeze slightly later.
So yes i call BS on this claim! LOL
Do it and prove me wrong. Is this a bs hoax now or did i get bad results. But how on earth can my results be bad when it took almost 3 hours to freeze in both cases ie a very slow process that within any experimental error can most definitely be correct within 5% since 3 hours is enough time for freezer to go over all possible cycles it does during the hour fairly similarly between the 2 cases.
That said maybe they have in mind some super fast freezers not the ones people have at home. But whatever, i am waiting your own results guys.
Lets define freezing at these 3 stages;
(takes at least 2 hours for me to get to part 1)
1) Early on water gets very cold and starts feeling heavy (as if it has higher viscosity)
2) A while later ice forms in the perimeter first in small segments
3) Several minutes later ice of depth 1-2 mm forms that covers the entire top exposed water surface of the can.
Go ahead and do it as well and tell what you get.
I am not surprised at your result, but I am not ready to call the original claim BS either. I still think the result of a specific test is going to depend on the geometry and moc of the container, the purity and history of both water samples, the temperature of the freezer and the starting temperature of the samples. I would bet that one could construct experiments that turn out both ways.
Let me give one example. Take the case of a hot sample at 100C and cool sample at 25C. Initially, virtually all of the heat transfer will be due to evaporative cooling at the surface, particularly for the hot sample. By the time it cools to 25C (which will happen quickly given the large driving force for cooling), the hot sample will have lost ~15% of its mass to evaporation. Therefore, it should take about 15% less time for it to get from 25C to frozen (all other things being equal), then the cool sample. If the freezer is not real cold, then the 15% reduction in the slow process of freezing could possibly be more important than the relatively fast process of cooling from 100C to 25C. MOC of the container is important because the more insulating the container is, the slower the freeze process and the more important the evaporative mass reduction is.
Try your experiment in a glass or plastic container. You might get a different result. Also, fully frozen versus a layer of ice is important. I am not sure how the original effect was measured.