Mpemba Effect

[Hittheroad]

I heard today there is a competition to see who can explain the Mpemba effect (hot water freezes faster than cold).
Physicists still don't understand this too well. Google it for more.

I can't explain it either but I may have found the first practical application. Ice cubes may not freeze overnight and if you drive off the next day what isn't frozen may end up all over your freezer and its contents (I have done the experiment). But using the Mpemba effect you should be able to get the ice frozen before you head off. I haven't yet tried this but the time difference is quite large so it should work.

(sorry I spelled the effect's name correctly in the text but not in the title - but I can't see how to edit the title.)

 

[ntsqd]

My ROP Industrial Plant Mechanics instructor, way back in HS, phrased it like this: "The more radical the temperature difference, the more radical the reaction." He illustrated this by pouring cold water into a styrofoam cup 3/4 full of R-12 refrigerant. (Kinda dates me there, doesn't it?) That made the coolest looking ice sculpture! Then he poured hot water out of the tap into a second cup of R-12. It blew the cup apart and evaporated the R-12 and the water! The only demo that he ever did that made a bigger impression was the oxy-fuel balloon.....

 

[Hittheroad]

My ROP Industrial Plant Mechanics instructor, way back in HS, phrased it like this: "The more radical the temperature difference, the more radical the reaction." He illustrated this by pouring cold water into a styrofoam cup 3/4 full of R-12 refrigerant. (Kinda dates me there, doesn't it?) That made the coolest looking ice sculpture! Then he poured hot water out of the tap into a second cup of R-12. It blew the cup apart and evaporated the R-12 and the water! The only demo that he ever did that made a bigger impression was the oxy-fuel balloon.....

I am impressed with the demo. But I do not understand what the fourwheelcamper is going on. I hope I am not being too expressive. But I want to stress how amazing this is. An effect known for over 2,000 years and under active discussion in the physics community since the 1970's still has no explanation as to how it works.

 

[Chukar Hunter]

Love the oxy fuel ballon experiments I used to do!