The molecular force of water expansion
IamSmooth, Mon Apr 30 2007, 02:40AMWater expands when it freezes. If I am correct, I think it has maximum expansion at 4 C. Anyway, does anyone know how much force freezing water generates? If I filled a strong cylinder with water, placed a force gauge at the top and began to freeze the liquid, how much force can it exert?
Re: The molecular force of water expansion
ragnar, Mon Apr 30 2007, 03:48AM
Freezing water can exert an unbelievable amount of force on any vessel it is contained in. You've probably shattered a glass vessel by absent-mindedly putting it in the freezer at some point.
Filling a hollow metal vessel with water and dropping it into liquid nitrogen... 'tis like a bomb going off.
ragnar, Mon Apr 30 2007, 03:48AM
Freezing water can exert an unbelievable amount of force on any vessel it is contained in. You've probably shattered a glass vessel by absent-mindedly putting it in the freezer at some point.
Filling a hollow metal vessel with water and dropping it into liquid nitrogen... 'tis like a bomb going off.
Re: The molecular force of water expansion
Bored Chemist, Mon Apr 30 2007, 05:48AM
"'tis like a bomb going off."
Where does the stored energy come from?
Bored Chemist, Mon Apr 30 2007, 05:48AM
"'tis like a bomb going off."
Where does the stored energy come from?
Re: The molecular force of water expansion
Bjørn, Mon Apr 30 2007, 05:54AM
You get minimum expansion (maximum density) at 4 deg C. I have seen someone running a small car on freezing water that compressed oil to very high pressures. If you google phase diagrams for water you will find some details, for example the freezing point changes when the pressure increases.
Bjørn, Mon Apr 30 2007, 05:54AM
You get minimum expansion (maximum density) at 4 deg C. I have seen someone running a small car on freezing water that compressed oil to very high pressures. If you google phase diagrams for water you will find some details, for example the freezing point changes when the pressure increases.
Re: The molecular force of water expansion
IamSmooth, Mon Apr 30 2007, 01:23PM
The question is, however, does anyone actually know the force it can exert? There has to be a limit.
IamSmooth, Mon Apr 30 2007, 01:23PM
The question is, however, does anyone actually know the force it can exert? There has to be a limit.
Re: The molecular force of water expansion
Dr. Shark, Mon Apr 30 2007, 02:18PM
The number depends on the ambient temperature.
shows that within certain limits you can sqeeze ice into water, and that ice can take denser structures that the normal modification.
To find the exact pressure you can generate at a fixed temperature would probably require a constant volume P-T diagram which a quick google search does not turn up. Maybe bored chemist knows more?
Dr. Shark, Mon Apr 30 2007, 02:18PM
The number depends on the ambient temperature.
shows that within certain limits you can sqeeze ice into water, and that ice can take denser structures that the normal modification. To find the exact pressure you can generate at a fixed temperature would probably require a constant volume P-T diagram which a quick google search does not turn up. Maybe bored chemist knows more?
Re: The molecular force of water expansion
IamSmooth, Mon Apr 30 2007, 04:32PM
According to the graph 2 kbar should revert ice to water until -20C. This is about 2000 atmospheres which is quite a force. Still, someone must have done a constant volume/pressure curve for water as the temperature is dropped below freezing.
IamSmooth, Mon Apr 30 2007, 04:32PM
According to the graph 2 kbar should revert ice to water until -20C. This is about 2000 atmospheres which is quite a force. Still, someone must have done a constant volume/pressure curve for water as the temperature is dropped below freezing.
Re: The molecular force of water expansion
Swany, Fri Jun 01 2007, 05:36PM
There is a limit, if you look at a phase diagram containing various forms of ice, ice I (the sort we know, ~0.92g/cc) is the least prevelent. In General Chemistry by Pauling, there is such a diagram and it shows about 9 types of solid water, ice I is the only with a density of <1g/cc. This thread is long dead, but under varying amounts of pressure and temp, other ice forms will prevail and there will be no exerted force.
Swany, Fri Jun 01 2007, 05:36PM
There is a limit, if you look at a phase diagram containing various forms of ice, ice I (the sort we know, ~0.92g/cc) is the least prevelent. In General Chemistry by Pauling, there is such a diagram and it shows about 9 types of solid water, ice I is the only with a density of <1g/cc. This thread is long dead, but under varying amounts of pressure and temp, other ice forms will prevail and there will be no exerted force.
Re: The molecular force of water expansion
Bored Chemist, Sat Jun 02 2007, 03:50PM
I on't have the data to hand but I remeber seeing an article in a journal using this as a means to generate gigh pressures with no real moving parts (except the water) 2 vessels made of thick stainless stell conected together and filled with water. Freeze the water in one and the expanding ice forces water out of the cooled vessel into the other one raisind the pressure. The authors pointed out that if you got the cooled vessel cold enough the ice contracted (and/or changed phase) so there was a limit to how high a pressure you could achieve; they counted this as an advantage on safety grounds. IIRC dry ice was cold enough to do the job
Bored Chemist, Sat Jun 02 2007, 03:50PM
I on't have the data to hand but I remeber seeing an article in a journal using this as a means to generate gigh pressures with no real moving parts (except the water) 2 vessels made of thick stainless stell conected together and filled with water. Freeze the water in one and the expanding ice forces water out of the cooled vessel into the other one raisind the pressure. The authors pointed out that if you got the cooled vessel cold enough the ice contracted (and/or changed phase) so there was a limit to how high a pressure you could achieve; they counted this as an advantage on safety grounds. IIRC dry ice was cold enough to do the job
Re: The molecular force of water expansion
Shaun, Thu Jun 21 2007, 04:37AM
This how ice skates work, by pressing ice into a thin layer of water, but i'm sure I can't possibly be the only one to know that.
I once heard of a case where burglars stole all the money from an outdoor ATM by filling it with water thru its various slots on a cold night via a small van-mounted pump. The water began to cool, expanded, and broke various bolts and welds holding the device together. They either pried it open or it fell apart, and they were able to get their [soaking wet] cash out.
I don't know if this is true or not; and i would think they would have to seal a lot of leaks as i'm sure those things arent watertight.
Shaun, Thu Jun 21 2007, 04:37AM
This how ice skates work, by pressing ice into a thin layer of water, but i'm sure I can't possibly be the only one to know that.
I once heard of a case where burglars stole all the money from an outdoor ATM by filling it with water thru its various slots on a cold night via a small van-mounted pump. The water began to cool, expanded, and broke various bolts and welds holding the device together. They either pried it open or it fell apart, and they were able to get their [soaking wet] cash out.
I don't know if this is true or not; and i would think they would have to seal a lot of leaks as i'm sure those things arent watertight.
Re: The molecular force of water expansion
Bored Chemist, Thu Jun 21 2007, 10:42AM
The idea of ice melting under skaters is a myth.
The effect of pressure on freezing point is only about a hundredth of a degree per atmosphere. With something like a couple of hundred pounds of skater on a blade a tenth of an inch thick and a foot long the melting point would only rise by about a quarter of a degree. So unless the ice was between 0 and -0.25 C to begin with it wouldn't melt. It's perfectly possible to skate at 20 below. At that temperature the ice would only melt if the pressure were something like 2000 atmospheres or 30000PSI. I dont think that skates would get anything like that pressure.
Bored Chemist, Thu Jun 21 2007, 10:42AM
The idea of ice melting under skaters is a myth.
The effect of pressure on freezing point is only about a hundredth of a degree per atmosphere. With something like a couple of hundred pounds of skater on a blade a tenth of an inch thick and a foot long the melting point would only rise by about a quarter of a degree. So unless the ice was between 0 and -0.25 C to begin with it wouldn't melt. It's perfectly possible to skate at 20 below. At that temperature the ice would only melt if the pressure were something like 2000 atmospheres or 30000PSI. I dont think that skates would get anything like that pressure.
Re: The molecular force of water expansion
atomicthumbs, Mon Nov 05 2007, 09:17PM
Well, way back when (around the 30s or 40s), some scientist filled a 4-inch-thick bombshell with water, screwed on the cap, and left it outside in the snow for a night.
He came back in the morning and the thing had a nice neat crack all the way around.
atomicthumbs, Mon Nov 05 2007, 09:17PM
Well, way back when (around the 30s or 40s), some scientist filled a 4-inch-thick bombshell with water, screwed on the cap, and left it outside in the snow for a night.
He came back in the morning and the thing had a nice neat crack all the way around.
Re: The molecular force of water expansion
Bored Chemist, Tue Nov 06 2007, 06:49AM
Bomb shells are designed to break.
Bored Chemist, Tue Nov 06 2007, 06:49AM
Bomb shells are designed to break.
Re: The molecular force of water expansion
Dr. Dark Current, Tue Nov 06 2007, 02:01PM
Dr. Dark Current, Tue Nov 06 2007, 02:01PM
Bored Chemist wrote ...
.. on a blade a tenth of an inch thick ...
Do you really think the blade is so thick? I'd say you're off by a factor of 10 at least... on a blade a tenth of an inch thick ...
Re: The molecular force of water expansion
Bjørn, Tue Nov 06 2007, 06:25PM
Some sports have a minimum width of 2.9 mm in the safety regulations and they work fine. A chair sledge has a much wider blade and it works fine too, both on ice and snow.
The rubbing action is probably much more important than the pressure itself.
Bjørn, Tue Nov 06 2007, 06:25PM
Some sports have a minimum width of 2.9 mm in the safety regulations and they work fine. A chair sledge has a much wider blade and it works fine too, both on ice and snow.
The rubbing action is probably much more important than the pressure itself.
Re: The molecular force of water expansion
Electroholic, Tue Nov 06 2007, 07:33PM
and the ice isn't not perfectly flat.
Electroholic, Tue Nov 06 2007, 07:33PM
and the ice isn't not perfectly flat.
Re: The molecular force of water expansion
Smlizz, Tue Nov 06 2007, 08:08PM
Here is a video of water in a cast iron shell in a dry ice bath. link
Smlizz, Tue Nov 06 2007, 08:08PM
Here is a video of water in a cast iron shell in a dry ice bath. link
Re: The molecular force of water expansion
Shaun, Tue Nov 13 2007, 02:32AM
That video is crazy..really puts things in perspective
Now we need a galv iron pipe and a vat of LN2!
Shaun, Tue Nov 13 2007, 02:32AM
That video is crazy..really puts things in perspective
Now we need a galv iron pipe and a vat of LN2!
Re: The molecular force of water expansion
Pete, Wed Nov 14 2007, 12:33AM
goood lord... That's is a sufficient video. I will ALWAYS put proper amounts of antifreeze in my radiator.
Pete, Wed Nov 14 2007, 12:33AM
goood lord... That's is a sufficient video. I will ALWAYS put proper amounts of antifreeze in my radiator.
Re: The molecular force of water expansion
rp181, Wed Nov 28 2007, 03:33AM
just speculating, i wonder if that force could be used to get energy from piezo electric materials? i dont know how much those give though
rp181, Wed Nov 28 2007, 03:33AM
just speculating, i wonder if that force could be used to get energy from piezo electric materials? i dont know how much those give though
Re: The molecular force of water expansion
Bjørn, Wed Nov 28 2007, 04:59AM
Yes it will work but it will be difficult to reach a significant efficiency. Piezoelectric crystals generally needs to be in resonance to give high efficiency. It is hard to see how that would work with freezing water.
Bjørn, Wed Nov 28 2007, 04:59AM
Yes it will work but it will be difficult to reach a significant efficiency. Piezoelectric crystals generally needs to be in resonance to give high efficiency. It is hard to see how that would work with freezing water.
Re: The molecular force of water expansion
rp181, Wed Nov 28 2007, 10:38PM
oh, didnt know about the resonance
would be cool if it worked though :)
rp181, Wed Nov 28 2007, 10:38PM
oh, didnt know about the resonance
would be cool if it worked though :)
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