Does hot water freeze faster than cold?

[music is magic]

A bucket of hot water will not freeze faster than a bucket of cold water.  However, a bucket of water that been heated or boiled, then allowed to cool to  the same temperature as the bucket  of cold  water , may breeze faster. Heating or boiling drives out some  of the air bubbles in water; because air bubbles cut down thermal conductivity, they can inhibit freezing. For the same reason, previously heated water forms denser ice than unheated water, which is why hot-water pipes tend to burst before cold-water pipes.

[argentus]

MiM, great to see you here.  

I believe that hot water will freeze faster than cold water, however it might depend upon several variables and factors, including ambient humidity, temperature of the experiment, and others.  

This interests me a lot.    I have been paring down my freezer over the past few weeks, trying to discard those odd containers which have become freezer-burned science experiments.   Thus, I have room.   I will undergo a few measured experiments and get back to you.   I think relative humidity will play a huge role, in that evaporation will radically change the freeze rate.   

​​​​​​​Update soon come.

[Halfswede]

It is not possible for hot water to freeze faster than cold water in and of itself.  This is simple thermo. While there are conditions where hot water will freeze faster, this is not due to the temperature alone, but the state -- the conditions in the experiment are no longer equivalent with temperature being the only difference.

All things being truly equal -- droplet particle size, gas content etc., cold will freeze faster. What happens in some of the winter videos is the near boiling water is already near an evaporative state. It is taken out into the very low humidity air and whipped into the air where some of it evaporates (cooling it quickly), and the rest is very small particles so it freezes very quickly. 

That said, all things are not equal with temp being the only difference. If you built a machine to push cold mist into the same air, it would freeze faster than the hot mist of the same particle size.  It's a gimmick of conditions rather than some twist of physics.

Evaporation plays two roles in these cases.  One, it cools the remaining liquid, and two it leaves less liquid to freeze, so in essence not as much of the hot had to freeze -- again invalidating the experiment. This is why true experiments like this require a closed system.

That said, there may be cases where you can leverage the phenomenon effectively regardless of whether it is a "fair" assessment of what is happening.

[Ravenwatcher]

Yes Hot freezes faster then cold , I had this happen last year Xmas morning water coming from the ceiling in my kitchen . This year I shut off the water to the pipes of the back of the house 1899 house no insulation in the walls and the wind just smashes the back of the house you'll freeze your toes in out pantry lol