Hot water makes ice cubes freeze quicker?

[Musicat]

@BoringDad

@Musicat

If “some of the water is very cold and some still very hot” then you don’t have a uniform sample and you have altered the question to “does hot water cool faster than cold water if non-uniform cooling or convection is allowed?”

The OP was not so precise as to include or rule out such things, so the question was not altered. As I stated, the blanket statement “Hot water freezes faster” is generally false. But if you press it, it becomes a question of semantics, heat transfer, volume, odd shape, surrounding conditions, etc.

The OP didn’t rule out this dialog, either:

Does hot water make ice cubes faster?

Yes. Put a tray of hot water in the freezer and leave a tray of cold water on the kitchen counter. The hot water will always freeze faster.

Unless the fridge is defective or the kitchen counter is in an unheated room in Antarctica.

@KidScruffy

The best explanation I’ve heard for this is the “Freezing momentum” explanation. Much like a ball rolling downhill which started on a higher, steeper hill can overtake a ball that started much lower, hot water as it freezes gains freezing momentum - so the water that started at 90 degrees will be cooling at a much faster rate once it hits, say, 30 degrees than will the water that started at 30.

No cite, but it just kind of ‘feels right’, doesn’t it?

Not to a physics major, it doesn’t. See my previous posts:

@Musicat

Please propose a test where, given two samples of pure H2O, at exactly the same temperature, you can tell which one was hotter a few minutes ago from merely testing the samples.

[CookingWithGas]

@Musicat

Not to a physics major, it doesn’t. See my previous posts:

Dude, it was a joke. See previous posts from a week ago.

[Musicat]

@CookingWithGas

Dude, it was a joke. See previous posts from a week ago.

:dubious: In that case, we need a whoosh smiley.

[CerebralZombie]

Actually, hot water has a lower capacity for dissolved gases than cold water. The oceans have a lot more life in the very cold places like the arctic than they do in the equatorial regions, because the water has lots more oxygen dissolved in it.

There is more oxygen in the Arctic ocean not because it’s cold, it’s because the ice there is full of oxygen. Animals were a lot bigger when dinosaurs were around because the oxygen levels were much higher then. After the ice age, tons of the worlds oxygen was frozen.

[JBDivmstr]

@CerebralZombie

There is more oxygen in the Arctic ocean not because it’s cold, it’s because the ice there is full of oxygen. Animals were a lot bigger when dinosaurs were around because the oxygen levels were much higher then. After the ice age, tons of the worlds oxygen was frozen.

Cite? :dubious:

[Cayuga]

@CerebralZombie

There is more oxygen in the Arctic ocean not because it’s cold, it’s because the ice there is full of oxygen. Animals were a lot bigger when dinosaurs were around because the oxygen levels were much higher then. After the ice age, tons of the worlds oxygen was frozen.

Best combination of user name and resurrection of zombie thread ever.

[Cayuga]

For what it’s worth, many years ago I filled two identical ice trays, one with hot tap water and one with cold tap water. The cold water froze much more quickly.

The OP is welcome to use me as a cite, if s/he is still around.

[clairobscur]

@Quercus

Just one question on this: if the ‘dangerous minerals and elements’ aren’t already in the tap water coming into the water heater, how do they get there?.

I never heard of “dangerous minerals and elements”. However, I’ve heard about dangerous bacterias that can multiply more readily in hot water, leading to stricter norms (In fact I was talking about this very subject with a friend who is a plumber yesterday).

[Der_Trihs]

@CerebralZombie

There is more oxygen in the Arctic ocean not because it’s cold, it’s because the ice there is full of oxygen. Animals were a lot bigger when dinosaurs were around because the oxygen levels were much higher then. After the ice age, tons of the worlds oxygen was frozen.

:dubious: Uh, if the poles were cold enough to freeze oxygen, the rest of the planet would be frozen solid too.

[dougrb]

Doesn’t make any sense to me, but…

Why Hot Water Freezes Faster Than Cold—Physicists Solve the Mpemba Effect

[KarlGauss]

@alterego

This is my fav explanation: Can hot water freeze faster than cold water?

This a great link*. Very informative, very clear. Thanks for pointing it out.

*ETA - which, evidently, not all posters in this thread have looked at.

[TimeWinder]

@KarlGauss

*ETA - which, evidently, not all posters in this thread have looked at.

It may have been less available eight years ago, when this thread was started.

But even given the zombie nature, the Mpemba Effect is more of an “exception that proves the rule” case – it’s not usually true, nobody’s been able to convincingly determine why it happens, and it’s an effect dwarfed by by other variability in most cases. I’ve heard a fair number of scientifically respectable folks claim it still hasn’t been shown not to be experimental error (it’s very, very hard to cool things identically).

I wouldn’t rely on it working to make your ice cubes freeze faster.

[KarlGauss]

@TimeWinder

It may have been less available eight years ago, when this thread was started.

Hmmm, not sure what you mean. It was posted one day after the OP, back in 2006.

[TimeWinder]

Sorry, talking about different articles.

[jtur88]

If water at 10 degrees freezes in X minutes, water at 30 degrees will take Y minutes to go down to 10 degrees, and then will take X more minutes to freeze. So 10 degree water will take X minutes, and 30 degree water will take X+Y minutes, and Y is always positive. So X+Y is always greater than X, and hot water will take longer to freeze. Unless somehow the temperature gradient skips 10 degrees on the way down.

[Punoqllads]

Thank you for not reading references which show experimental evidence that you’re wrong as well as physical explanations as to why you’re wrong.

[jtur88]

@Punoqllads

Thank you for not reading references which show experimental evidence that you’re wrong as well as physical explanations as to why you’re wrong.

They only show that it is possible in a laboratory to create conditions under which warmer water will freeze faster than colder water. But it has not been shown that a container of warm water that is exactly identical in all physical respects as
an identical container of cooler water will freeze first. It requires a set of circumstances in which the warm water becomes significantly different during initial cooling, than the water which has already been prepared for freezing in its cooler state.

In other words, it is not correct to say hot water WILL freeze before cold water, it shows that under certain circumstances, hot water CAN freeze before cold water. Considering the premise if the thread, it is not ta general scientific truth that Hot water makes ice cubes freeze quicker

[Punoqllads]

@jtur88

They only show that it is possible in a laboratory to create conditions under which warmer water will freeze faster than colder water.

Did you read about how Aristotle and Descartes also noted the same effect? Did you read about how the Mpemba Effect was well known among Tanzanian ice cream makers? Do you think they did those observations under laboratory conditions?

But it has not been shown that a container of warm water that is exactly identical in all physical respects as an identical container of cooler water will freeze first.

You said: “So X+Y is always greater than X, and hot water will take longer to freeze.” This is wrong. Over seven years and fifty posts ago mhendo linked to the Straight Dope column that noted that which one freezes first depends upon initial conditions.

[jtur88]

The implication of this thread’s premise is that if you want to make ice cubes quicker, start with hot water. This is, as a general guideline to household ice cube making, a false premise. Starting with tap water out of the hot faucet will not yield ice cubes faster than starting with tap water out of the cold faucet. Nothing in any of the posts above “proved” that, in general application, “Hot water makes ice cubes freeze quicker”.

[The_Librarian]

Knowing only what I can see with my own eyes: if you take two identical glasses; fill one with warm water and the other with cold water; put both in the same freezer : the one filled with cold water freezes much faster. Which by a happy coincidence is exactly what thermodynamics predicts.

I call bullshit on the Mpemba effect. My assertion is that it is Tanzanian for ‘gullible fools are gullible’.

Anyone who has done the simple experiment, which can be done in every kitchen in 15 minutes, can confirm.