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prole
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Purity of store bought distilled water
Recently, I purchased a nice 4L amber glass jar, and decided that it needed to store pure water. I rinsed the jar with dH2O and distilled acetone to
remove any dusty residues, then dried it. Then I distilled 4L of store-bought distilled water (now twice distilled). What remained in the distilling
flask after all this was about 25 mL of milky, translucent residue, not unlike watery skim milk. I figured that this may happen, and it's probably no
surprise to you, the estimable mad scientists, but I felt compelled to post this here. This new, purer water is now to be used whenever dH2O is
called for in a reaction. It is reasonably safe to assume that no foreign matter is present to offset a reaction.
This is posted for informational purposes only. Distillation of water should only be performed by a qualified, competent professional (which I am
not). 
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neutrino
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Really? I've always used my water straight from the jug and never had any problems. It will dissolve AgNO<sub>3</sub> without a trace of
cloudiness, so I figure it's clean.
What brand of water are you using? Mine is Richfood (yes, the cheapest one).
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prole
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I'm using Absopure. It's supposed to be 'absolutely pure'. Although I've never had problems with using it straight from the jug, I doubted it's
purity, whatever the brand. After distilling 4 litres, I finally proved to myself that it was indeed impure. It's probably a negligible amount of
crap (plastic particles, dust, processing contamination), but for purity nuts, distilling may be the way to go.
It may be important to note that the cloudy residue was the result of 4L distilled without ever changing the distilling flask. More water was added
as the level dropped. This was a leap of faith on my part, I wasn't sure if there were impurities. I was happy and sad to find I was right. Knowing
this makes me sleep that much better at night (and some Saturday afternoons).
It should also be noted that I used 'distilled water', and not 'spring water'. Both are offered by Absopure.
[Edited on 3/16/2006 by prole]
[Edited on 3/16/2006 by prole]
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BromicAcid
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My regular brand of distilled water was used to dillute the nitric acid that I used to make my silver nitrate. After dissolution there was not a hint
of cloudiness and despite me boiling it to dryness there was no decomposition that can be associated with less then pure ingredients.
But then again different jugs of distilled water have different tasts so there has to be something in there, expecially in some of the brands that I
can hardly even stomac. I mean, it's distilled water, they should all be the same! The components either arise through leeching of the jug they come
in, or they are simply things that distill over with the water. It is afterall only distilled water, not carbon filtered distilled water.
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lordmagnus
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Water Quality
Hummm, that is curious...
It maybe elements that leached from the cheap plastic in the bottles, I've been using R.O (reverse Osmosis) water that is treated with OZONE to
preserve it's sterility. I may run a test soon on the last half galon I have, run it thorugh the 1000ml flask with a liebig condneser, and see what
remains when all is said and done
I\'ll kill a man in a fair fight, or if I think he is gonna start a fair fight, or if he\'s bothrn me allot, or if I am getin payed good, or probably
over a good woman.
-Jayne Cobb (Serenity) |
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MadHatter
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Glass
I like to distill my own water using glass. 1st, its absolutely tasteless and, 2nd, it keeps most of
the metal cations out. IIRC, commercially, and all the home water distillers from Sears, JC Penny,
etc., use stainless-steel vessels to boil the water. Now, the cations aren't a problem unless it's
for hydrazine using the ammonia/bleach combination. The cations can catalyze the intermediate
chloramine into ammonium chloride and I like to use my gelatin solution sparingly because of
it's cost.
Otherwise, cheapass distilled water that is nearly tasteless is great for fractional crystallization.
From opening of NCIS New Orleans - It goes a BOOM ! BOOM ! BOOM ! MUHAHAHAHAHAHAHA !
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jack-sparrow
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Maybe Absopure distilled water is a hoax. Did you try to acidify the residue? If it bubbles it is contains probably carbonates which means that the
Absopure distilled water is partially purified Absocrap spring water !
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prole
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studur - I didn't save the residue, but that might have been a fun experiment. I was just glad to be rid of it. My money's on plastic leachate as
the primary contaminate. I've read that we all get a fair amount of plastic in our diet, which may or may not lead to health issues down the road,
and this is why I decided to undertake this project, to see if it might be true. I suppose I'll have to distill another 4L to find out, but not
today.
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vulture
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I was shocked to find that a mixture of 50% pure isopropanol and 50% distilled water left a distinct spot on glass when it evaporated.
I'll have to put my water under more scrutiny it seems. 
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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unionised
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I guess the stuff left behind was extracted from the plastic so there's a fair chance that it's phthalate or one of the bisphenol derivatives that the
press love to call "genderbending".
Anyway, an amber glass container will almost certainly leach alkali into your pure water. Even if it doesn't the water will still pick up CO2 from the
air. That's the probem with pure water- it doesn't like to stay that way.
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lacrima97
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So you are saying that the amber glass bottle can contaminate the water???
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12AX7
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I suppose there isn't anything that won't contaminate, well maybe a bottle made of HgS, that's pretty damned insoluble stuff, but yeah, the sodium and
calcium ions on the surface can be leached, even the silica tetrahedra can dissolve. Not to mention everything adsorbed on the surface. But geez,
this is all ppm if not ppb level, ain't it? Detectable, but insignificant outside of rinsing in-process silicon wafers..or something.
Tim
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woelen
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I agree with 12AX7. Although distilled water, as purchased from hardware stores, may have some impurities (e.g. from the plastic bottle), I've never
had problems with it. Solutions of silver nitrate remain perfectly clear and even the exceedingly sensitive basic vanadate (IV) solutions remain clear
in that water, while the latter give a thick flocculent precipitate with our tap-water (which is not bad at all).
So, in practice, I have no problems with the distilled water I have. The only time, when it might give problems for me is if I have to isolate a few
grams of dissolved matter from liters of water, but I do not have that kind of experiments at home.
Btw, I also tested my distilled water and it leaves very faint stains, when a large drop is allowed to dry on a clean piece of glass. But, I have to
say, this may also be due to invisible impurities on the glass, which dissolve in the water and then settle at the glass in another pattern than on
the other parts of the glass. I observe the same effect with all other solvents I have (e.g. 99.9% methanol, diethylether, acetone).
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prole
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Like everyone else here, I've never had problems with the various brands of dH2O I've used. But perhaps unlike some here, I'm a bit particular
(understatement here) about stuff that doesn't belong to a particular molecule ending up in one (read: purity nut). Besides, I like to grow crystals
for fun, and I don't want gender-bending dust/particles/residues/foreign matter influencing the ultimate shape of it. (No bias towards transgender
people, only chemistry). I'm sure only a Scanning Electron Microscope or other fancy-schmancy high-tech gizmo would be able to detect the minute
amounts of crap in my crystals, but the more I can eliminate, the better I feel. Plus, I wanted to see what distilled water residue looked like.
Now I know.
[Edited on 3/19/2006 by prole]
Yeah yeah, I know, you can't grow crystals of molecules.
[Edited on 3/19/2006 by prole]
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neutrino
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What makes you say that? Sucrose is a molecule and plenty of people have seen sugar crystals. 
[Edited on 19-3-2006 by neutrino]
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prole
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Ever try growing megacrystals of sugar? Can't do it. Large crystals can only be grown from ionic substances.
One of these days, when I become technically proficient, I will upload my photos of my crystal collection, that is, if anyone's innerested.
[Edited on 3/19/2006 by prole]
[Edited on 3/19/2006 by prole]
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12AX7
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Hum, I don't see why not, long-range order in a molecular substance is probably going to be worse than an ionic, but nonetheless, if molecules can be
arranged on a small scale, they can always be added to the crystal faces, if not necessarily evenly.
Personally I'd love to see some crystals
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jack-sparrow
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Pure enough !
I am working in a deuterated chemical factory. We make deuterated solvents for NMR. We store all our solvents in amber glass bottles with teflon caps.
If anybody is concerned about any contamination/leeching please don't. I use oven dried flasks blown with nitrogen (to remove humidity and dust)
straight from the box and I have never had any problem storing NMR solvents at 99.96% deuterium content. I really think that the water you use is pure
enough for ANY chemical reactions you want to do. We make our own deionized heavy water (D2O) at 0.00±1 mS conductivity and we store it in cheap
polyethylene barrels. Hydro-Ontario told us that it was perfectly pure. So if it is pure enough for a nuclear reactor, it must be OK for anybody on
this planet dont you think so ? So the container is not your contamination source. It is most probably 1) the chemist or 2) the purification. If you
have 10 mg of residue in 4 kg of water we are talking about 2.5 ppm which is practicaly nothing. It wont screw up your reactions. You are a most
probable source of experimental failure than 2.5 ppm of crap in your water.
Sorry if it sounds rude but I do the same mistake sometimes. We have to stop and think about what is significant and what is not.
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prole
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No sweat, studur. I new I might catch some flack for my pickiness. As stated above, no one has problems with their water. But what I saw in my
flask was like skim milk, and that screamed 'IMPURE!'. It was an experiment, you know. The water I distilled is only going to be used for certain
experiments for special reactions and/or crystal growing, as further experiments. For the rest, good ol' dirty distilled water will suffice.
I would have liked to post a photo of it here, but 1) I only have black 'n white film, 2)no digital camera, 3)don't know how to post photos yet 4) too
cheap to buy colour film (a bias agains films of colour). But I'm working on it.
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12AX7
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| Quote: | Originally posted by studur
We make our own deionized heavy water (D2O) at 0.00±1 mS conductivity and we store it in cheap polyethylene barrels. Hydro-Ontario told us that it
was perfectly pure. So if it is pure enough for a nuclear reactor, it must be OK for anybody on this planet dont you think so ?
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Conductivity of... 1 cm cube? 1km rectangle? Where are the probes? I'm totally pissed at hearing of "16.7Mohm" pure water, megohms of WHAT!!!
(Nothing personal.)
The other thing, a nuclear reactor isn't exactly clean, that fuel makes a lot of trash after all! I highly doubt they really care about ppm's of
anything, although if they do you'd know better than me. The deuterium content would be a concern, though.
Tim
[Edited on 3-20-2006 by 12AX7]
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jack-sparrow
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Measure unit definitions
mS means milli - Siemens. The Siemens (S) is the measure unit for electrical conductivity. Ohm is the unit for electrical resistance. The lower the
measure in mS is, the lower is the conductivity. You need ions to conduct electrical current. If the conductivity is low, then the water is low in
ions (I am not talking about H+ and OH- ions of course ut electrolytes likes metal cations and anions like chlorides, sulfates, phosphates, etc.).
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12AX7
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Ya I know. Siemens work for the conduction of objects. You kind of have to define the geometry. Resistivity (or conductivity) is in units of ohms
times length per area!!
Tim
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jack-sparrow
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V=RI
Volt=Ampere*Ohm
Ohm=Volt/Ampere
conductivity = 1/resistivity
Siemens = 1/ohm = ampere/volt
ampere = 1 coulomb/sec
1 coulomb = 6.2*10^18 electrons
volt = (kg*m^2)/(s^2 * coulomb) or (kg*m^2)/(s^3*A)
You should have all what you need
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12AX7
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So, no matter the seperation or area of the electrodes, my ohmmeter will ***ALWAYS*** read 1 megohm in this stuff?
Tim
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neutrino
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Resistance is still based on geometry. All things being equal, a homogeneous block of graphite 2 cm thick will have twice the resistance of a block 1
cm thick. You cannot calculate the resistivity from resistance without geometry.
For those who are unfamiliar with the subject, see this page.
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