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Name: Al
Status: educator
Grade: 9-12
Country: USA
Date: Winter 2009-2010


Question:
I am a high school chemistry teacher who keeps jugs of distilled water in my room for the purpose of making solutions. I have experienced some bizarre behavior from these jugs of water and would like to know what you make of it. Jugs of water will become half-full after sitting for a period of only one or two months with no leakage. The lids are still firmly sealed. Jugs of water will develop splits (not along the seam) through which water will leak. Jugs of water will shrink and deform as if someone has placed a heavy load on them (which no one has). And the most mysterious occurrence of all - as I am lecturing, all of a sudden a jug will actually explode as if struck by a bullet. My room does not experience temperature swings that would account for thermal shock and no one is in my room (I keep it locked) when I am away.



Replies:
I am not sure I can resolve your problem. It sounds weird. However, the solution to the problem is to change containers. Use glass jugs instead of "plastic". Glass has had several centuries of testing for the storage of distilled water. That is a pretty good track record. If you continue to have a gas pressure buildup, you probably would have to look at some sort of microbial growth. But I suspect you just want to problem to go away. Another suggestion is to clean and rinse the storage containers on a more frequent schedule.

Vince Calder


Al,

One issue I always had storing distilled water is that it absorbed carbon dioxide from the air and becomes very acidic. pH of 4 or lower by some test observations. Since I would use this water for activites that often involved living materials, I used a buffer to neutralize the acidic quality of the water, but that may defeat your purposes. My idea is that you may have some chemicals sublimating nearby that is reacting with the acidic quality of the water or the pH is having a detrimental effect on the plastic. Aged plastics often do not behave as predicted.

Using glass and making the container air tight may solve your issues.

Steve Sample


Al

Your experience is truly unique. What are your jugs made of? How is the lid sealed on (Screw top cap, cork, or something else?) What is the volume of your jug, a liter?

Is it possible someone took some water out of the jugs without you knowing it? Evaporation is the only other possibility I know of, but half the volume over a month is too much to account for evaporation.

Sincere regards,

Mike Stewart


Have you tried exorcism!! Seriously, what is the material of construction of the jugs? It sounds like the water is extracting a water soluble component from the plastic jug. This is weakening the walls and also making them brittle, hence subject to "catastrophic" failure. The pressure collapse suggest a process similar to the crushing of a paint can by the atmosphere when the air in the can is expelled by boiling water, and the can's spout is sealed by tightly screwing it on.

I would alter the jugs and inform the vendor. Ask for a refund and replacement by another material. Show the vendor the results of one of your "events".

Vince Calder



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