A Science Question

[Nanohedron]

Plasticular atrophy.

[dwest]

I used to hike near the top of a mountain near Tucson, Arizona. I would close my plastic drinking bottle on top of the mountain (9,000 ft. elevation), get in my car and drive down the mountain to the valley floor (3,000 ft. elevation). I often found myself startled to find that my nearly empty drinking bottles had become totally crushed by the higher atmospheric pressure of the lower elevation.

Another example is how when I got off the airplane on Sunday, and opened my Sigg bottle to have a drink, it spewed at me.

That's why you take along a Platypus when you travel up and down different altitudinal zones, plus they're cute and good company. Of course if you have a Camelbak you may not want a Platypus. Oh! And don't forget the Ospreys

[mutepointe]

Thin-walled plastic containers that are sealed will flex as the ambient atmosphere pressure changes. Polyethylene will easily flex with the changes, but over time this continual flexing will cause failure of the material, often at the edges of folds or creases caused by the flexing. An extreme example of the effect of atmospheric pressure can be easily seen if you drive in mountainous areas. I used to hike near the top of a mountain near Tucson, Arizona. I would close my plastic drinking bottle on top of the mountain (9,000 ft. elevation), get in my car and drive down the mountain to the valley floor (3,000 ft. elevation). I often found myself startled to find that my nearly empty drinking bottles had become totally crushed by the higher atmospheric pressure of the lower elevation.

The above example is a good reason that flammable liquids or other hazardous materials need to be kept in containers that have been especially designed for this use.

Maybe this compound and container are working just as God intended. Maybe the failure is with your perspective Doug. I know there is failure with your Poll Making.

[Doug_Tipple]

Maybe this compound and container are working just as God intended. Maybe the failure is with your perspective Doug. I know there is failure with your Poll Making.

I don't pretend to know the intentions of God, not do I spend much time worrying about that, but as someone who worked for several years as a laboratory supervisor in materials testing (destructive and non-destructive) in the aerospace industry, material failure is a commonly-used term. In designing with any material, it is important to know the physical limits of that material, otherwise you have bridges that collapse, containers that leak or explode, etc.

With regard to the third sentence above, maybe your criticism of my poll making is a failure of your perspective, Mute. I could sing that, "My poll is better than your polls, My poll is better than your polls", but I won't.

[highland-piper]

Distilled water contains only H20 molecules, so it has lost its ions, because these require the presence of other molecules in solution (usually in the form of salts, iirc) with water.

Water really likes to have ions around, and it likes them so much that it can break the ion bonds in other material and take over what it wants. One such material is plastic. Distilled water will corrode plastic like an acid* over time. For long term storage, you need to keep it in glass, not plastic.

*which it is, actually, in that distilled water has very low ph.

Over what time frame?

I've had a bottle of distilled water in my cabinet for a decade now.

I picked defective container, but if "user error" was an option I'd have gone for that in a heartbeat.

[s1m0n]

Over what time frame?

I've had a bottle of distilled water in my cabinet for a decade now.

It depends on the volume of the water and the kind of plastic. If the quantity is small and the plastic generous, the water can get enough ions before the bottle corrodes. At that point, what you have is a bottle of water, not a bottle distilled water. The water will have returned to its commonest stable state - a saturated solution of H2O, salts, carbon dioxide, and/or minerals. Also, if the cap's not tight, the DW can absorb atmospheric CO2 which will also slake its need for solutes. Ten year old DW likely went back to being just plain old water years ago, unless it's had some kinda hermetic seal.

~~

Seriously - 'keep distilled water in glass for long-term storage' is not weird advice. This is a well understood part of chemistry.

This link suffers a bit from newage pseudo-science, but the basic thrust is correct:

Water is a strong solvent; therefore, it carries many invisible substances: minerals, oxygen, nutrients, waste products, pollutants, etc. Pure water without any substance is as un-natural as a pocket of vacuum within a normal atmosphere. A pocket of vacuum will suck in any and everything around it until the pressure becomes equal to the surrounding.

Likewise, pure water will leach out any and every substance that it can dissolve from the substances that it comes into contact with, until its content is homogeneous with its surrounding or the water is saturated with substances so that it can no longer dissolve anymore substances.

[...]

Distilled water and RO (reverse osmosis) filtered water contain no minerals, simulating close to pure water. This pure water should be neutral with a pH value of 7. However, it measures acid pH! The reason for this phenomenon is that pure water sucks in carbon dioxides from the atmosphere. Although it measures acid pH, there are no acid minerals in that water. If pure water is stored in plastic bottle, the water smells plastic.

For this reason, distilled water or RO filtered water should be stored in glass bottles or special plastic bottles that can block carbon dioxide penetration. Coca Cola was bottled originally in glass bottles only. Then came the plastic bottle and it lost the fizzles. Then better plastic bottles came out that didn't lose carbon dioxides; still plastic-bottled Coca Cola has to have expiration dates. Carbon dioxides penetrate through plastics, making pure water acidic.

[mutepointe]

Maybe this compound and container are working just as God intended. Maybe the failure is with your perspective Doug. I know there is failure with your Poll Making.

I don't pretend to know the intentions of God, not do I spend much time worrying about that, but as someone who worked for several years as a laboratory supervisor in materials testing (destructive and non-destructive) in the aerospace industry, material failure is a commonly-used term. In designing with any material, it is important to know the physical limits of that material, otherwise you have bridges that collapse, containers that leak or explode, etc.

With regard to the third sentence above, maybe your criticism of my poll making is a failure of your perspective, Mute. I could sing that, "My poll is better than your polls, My poll is better than your polls", but I won't.

[dwest]

What a stitch, why so cross?

[missy]

long time ago, I used to run the atomic absorption instrument at work.

Distilled water and deionized distilled water will pick up all kinds of things dependent on what they are stored in. And depending on what we were analyzing for, we would store the water in glass, Nalgene, or have to make sure it was changed out daily.

Some plastic is also just plain "weak". It will change composition (I won't say entirely break down) over time, especially when exposed to temperature changes and light (particularly UV).

Water can absorb acrylamide from plastic, depending on what grade the plastic is.

Answer to your question - if you are going to store liquids for long periods of time, always have them on containing trays. At least - that's the lab safety person answer!!!