# 4th Grader asked me a strange question today.



## DownHome (Jan 20, 2006)

So I thought I would start here. If anyone knows or can direct me to a website, that would be great. 

He asked if cold turns anything to liquid. In otherwords, when heat typically melts things, is there anything that cold melts and heat solidifies?

Awesome question right? I had never even thought about that.

thanks all

downhome


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## Guest (Aug 7, 2009)

I can't think of anything that cold liquefies and heat makes solid, but there are many things that cold turns into a liquid. Water vapor for one, pretty much all gasses that I can think of though it make take extreme cold to do it.

Not precisely what he was asking since they don't start as solid before melting.

.....Alan.


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## deaconjim (Oct 31, 2005)

Cold liquifies gasses (air, nitrogen, oxygen, etc.). Heat will return those liquids to their gasseous state.


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## Ed Norman (Jun 8, 2002)

My nose.


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## Dente deLion (Nov 27, 2006)

deaconjim said:


> Cold liquifies gasses (air, nitrogen, oxygen, etc.). Heat will return those liquids to their gasseous state.


Right. Toss a butane lighter in the freezer to demonstrate. 

(Of course, don't let the child touch the lighter!)


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## DownHome (Jan 20, 2006)

Laughing at Ed...LOL!!

Thanks, I didn't even think of gases. I'll try to explain that to him. Scientist in the making 

downhome


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## ErinP (Aug 23, 2007)

Also, on the topic of heat, remember that there is scientifically no such thing as "cold." There is simply more heat, less heat, or the absence of heat (ie, absolute zero).

And yes, he's old enough to understand this.


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## Nevada (Sep 9, 2004)

The proteins in egg whites will become solid with heat, but it's not reversible. Likewise, if oil is heated to a very hot (1000F+) temperature it will be reduced to a solid carbon material called petroleum coke, but again it's not reversible.


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## PyroDon (Jul 30, 2006)

the only thing I can think of that will expand with cold and retract with heat are certain bi-metals


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## deaconjim (Oct 31, 2005)

Water is the only substance that expands with either cold or hot temperatures (at the extremes).


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## Ed Norman (Jun 8, 2002)

deaconjim said:


> Water is the only substance that expands with either cold or hot temperatures (at the extremes).


It's most dense at 4 degrees C, or else lakes would freeze on the bottom first and push all the fish out the top. Somebody was thinking when they invented that.


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## Joshie (Dec 8, 2008)

Nevada said:


> The proteins in egg whites will become solid with heat, but it's not reversible. Likewise, if oil is heated to a very hot (1000F+) temperature it will be reduced to a solid carbon material called petroleum coke, but again it's not reversible.


That's because a chemical change happens, not just a physical change.


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