Why does boiling water freeze faster than room-temp water?
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It doesn’t mostly. Basically under very specific (so specific that it is rarely replicated with the same setup) it does happen.
Temperature is, is how fast it vibrates. So a room temperature water vibrates slower than hot tap water. So ice being water vibrates even slower than room temperature water. Now if you put room temperature water into a freezer it will cool down and form ice by slowly vibrating less and less. If you have hot tap water it must cool down to room temperature AND then do the same as the room temperature water slowly vibrating less and less. So of course hot liquids DO NOT freeze quicker than room temperature ones. Mostly 🙂
Cooling between two things is very well described in physics. Containers can be multiple materials and surfaces areas with those materials calculating things can get really intricate but all of the maths relys on the average temperature in both materials. Which works well for everything we seems to calculate apart from this one effect that no one understands 😀
It is known as the Mpemba effect after its “discoverer”. Literally no one knows why it happens even him.
The story behind it is all described [here](https://en.wikipedia.org/wiki/Erasto_B._Mpemba). Our physics is pretty bloody good but this is a definite effect so something must be happening in a manner we don’t check.
I have a theory but have no empircal evidence (of course) if you (or anyone else) want a laugh. For ever material (from gold to air) has a value for how fast it transfers heat (ie its thermal conductivity). The value however differs based upon the state too. Water is 0.54 W/m2/C while ice is 2.22 W/m2/C and air is 0.023 W/m2/C (how you’d measure steam i don’t know it would be nightmare). As i stated earlier our working method for calculating cooling use average information because we cannot monitor all the molecules involved. There is cycling of compartively hot and cold parts of liquid as well as the air when they are exchanging heat. These currents of hot and cold create eddies given the right circumstance. Those currents are more pronounced in hotter liquids because they are hotter. I believe these little currents are allowing phase change to occur in isolated molecules but when they get trapped in this increased thermal conductivity state due to an eddie and it “snowballs”. Thermal conductivity uses surface area and if that area increases its going to cool more, faster. This logically could accelerate total cooling and so bypass a cooler drink being frozen. I’m sure someone with a decent physic simulation could attempt to model the fluid dynamics of the beaker and heat exchange if they wanted to but it would be a mammoth undertaking resource wise and frankly its not that important so it will likely stay a mystery.
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