Any scientists out there? ICE!!!

[Box_Of_Frogs]

Following on the earlier post about how to stop the water in troughs/buckets from freezing, my OH (civil engineer and MENSA member, though don't ask about common sense) absolutely insists that it has been "scientifically proven" that warm water freezes faster than cold. I have told him he is mad and that it's clearly an old wives' tale, UNLESS he can show me the scientific proof.

Do I need to practice a grovelling apology?????????????????

 

[Nailed]

Yes you seriously do...
Hot water freezes quicker than cold water.

Lou x

 

[Box_Of_Frogs]

Oh bugger. What's the science behind it then Lou?

 

[Allykat]

Yes it is true. I do not know the specifics other than I had a bright idea of pouring warm water on the lock of my car to get the key in. This did work but when I poured the remaining hot water on my windscreen it froze instantly to a thick sheet of ice as oppose to the soft crumbly frost that comes off relatively easily in comparison

 

[Nailed]

summit to do with, as the liquid is cooling down to the same tempa s the cool water some evaborates and lowers the surfaces are.. oh and summit to do with density of the wter being less allowing the cold to get in easier.. I cant truely remember. However it is known as the Mpemha efect i think..

PS I talk bollocks i warn you.

Lou x

 

[kit279]

Ok, well I might be able to shed a bit of light here. You are BOTH right. A bucket of hot water will take longer to freeze solid than a bucket of cold water, therefore you are correct. However, hot water poured onto a cold windscreen eg. to defrost, will actually evaporate faster. Evaporating water is the fastest way to cool something down eg. you throw water on your horse to cool him but really its the dampness rather than the water than cools him down. Therefore evaporating hot water on a windscreen will freeze faster than cold water on a windscreen. Therefore your OH is sort of correct but really he needs to grovel to you. Just generally, to get the practice..!

 

[Box_Of_Frogs]

That's good enough for me kit279! I'll get him the kneeling pads out now! And Lou, don't think you're off the hook coz I'm just off to Google "Mpemha"............................

 

[Nailed]

Was the spelling right? LOL
Lou x

 

[Nailed]

Im a div.. its Mpemba

Lou x

 

[Box_Of_Frogs]

Almost!!!!!

The Mpemba effect
Seemingly simple questions can lead to unexpected answers

Which takes less time to freeze: hot or cold water? The obvious answer from thermodynamics would be that cold water freezes first. But like other straightforward questions in physics, this one is far more complex than first meets the eye (see "Does hot water freeze first" Physics World April 2006 p19). Hot water, it seems, can freeze first, although not always. It all depends on what you mean by "freezing", how hot the liquids initially are, how much gas is dissolved in the water, what shape the containers are and so on. While some may view these as tedious complications to a trivial problem, it is one that has been mused over by no less than Aristotle, Francis Bacon and René Descartes, and is now known as the "Mpemba effect" after a Tanzanian schoolboy. Noticing that an ice-cream mixture cooled faster when initially heated, Mpemba failed to get a satisfactory explanation from his teachers, and a full understanding of the effect still eludes us. The story illustrates that while it is right to be sceptical of unusual results, we should neither mock the simple question nor dismiss the unexpected answer out of hand.

I'm so grateful for that Lou! I now have a stonking headache, am little the wiser and the only solution is to throw myself under a bus before OH gets up in the morning. x

 

[Allykat]

Ooooh well you learn something new everyday

 

[Birker2020]

Has anyone considered sprinkling a little salt on the surface of their water, or maybe a little vegtable oil. Surely this would stop it freezing? You can buy glycerol but I am not sure what quantity you would have to use and it would have to be food grade gycerol.

 

[Donkeymad]

You would need an awful lot of salt to stop water from freezing, and it would be unpalletable to horse, let alone dangerous.
Glad the secret it out about hot water!!

 

[Box_Of_Frogs]

Answered this in the earlier post about tips to stop water freezing. As Little Donkey says you would need a huge amount of salt in a bucket of water to lower the freezing point enough to stop it freezing. Think how a bucket of seawater would taste! And even if the horse would drink it (which I doubt) it would make it very ill. Putting a layer of oil on top of water has been shown in laboratory conditions to slow down the freezing of a bucket of water but, again, I can't see any horse plunging its nose into what would appear to be a bucket of oil to have a drink.

The secret isn't out about hot water! My OH sent me the link to a scientific paper and it seems this has puzzled great minds such as Descarte and Aristotle for centuries. In certain controlled situations, hot water will freeze faster than cold. But it depends on a host of things such as how many gases are dissolved in the water, the shape of the container, the insulation and even the definition of "freezing", ie just the surface or the whole bucket! The scenario where you chuck a kettle of boiling hot water over the car windscreen and it promptly freezes over is well understood but NO-ONE knows why hot water freezes faster than the cold in certain other conditions. I don't think it would in a yard situation. Certainly, I add warm water to my ned's bucket and it stays clear of ice longer than others but that doesn't prove anything. The scientific advice is to use de-icer spray on the car but it doesn't run to practical help with horses!

Thank god it's set to get milder over the next few days! This was bound to happen as I have just ordered my ned another rug.

 

[Solitaire07]

This is all a mystery to me! My friend wraps straw around her water buckets to stop the water freezing but my neddie just ate the straw! Roll on spring. Alison