I feel as if I've met an equal number of chemists with different attitudes about how strict they are on their water source. I seem to know an equal
number of chemists who either: A) insist on only using distilled water for all chemistry work, and B) only bother using distilled water when the
reaction calls for it, or when working on tiny molar scales. I realize that faucet water differs from city to city, wherein some cities it is
atrocious, and others it is exceptional. In my past years of hobby chemistry, I've almost exclusively used faucet water in reactions, and I have never
had any kind of issue with unexpected reaction results, however I also almost never work on micromolar-scales, so the ion:reagent ratio would always
be very small.
Earlier today though I noticed that distilled water adsorbs/clings to my classware entirely differently than the faucet water, with the distilled
water forming much smaller stable droplets, and the faucet water forming larger droplets. Intuitively this feels reasonable; ions in water would
reduce the waters electrostatic attraction to the glass. However the water I use is not that "hard" at all, and this difference in droplets was
visibly significant, far more than I would expect.
I recall reading a study several months ago where the authors were analyzing a reaction that [initially] appeared to be catalyzed by some simple
potassium salt of some kind. I forget what the salt was, but they noted that the reaction did not occur in the absence of it, and that their source
was some very pure 99.99%+ from a chemical supplier. However they were suspicious of the reaction so they tested it against the same salt from another
supplier, and no reaction occurred. Upon composition analysis of the two salts, they noticed that their initial source had tiny trace quantities of
palladium present, whereas the other did not. As most know, it is impossible to obtain true 100% purity of any compound, and that even at 99.99999%
increasing purity, there will always be some fractional residue that was present in the original source. In the majority of cases, such tiny
percentages will have no effect on a reaction, but in select cases, normally non-catalytic salts can behave as amplifiers of more catalytic metals
present in tiny quantities. In recent years such notions have given rise to theories of "superatoms" and "single atom catalysts", which focus on the
unexplored mathematical dynamics of atoms as quantum mechanical electronic oscillators in equilibrium with each other.
So, what are your experiences in terms of water sources? Have you encountered any reactions that appeared to run dramatically differently in distilled
water versus water that wasn't deionized? For example, some unusual oxidation/tar product which only appeared when you didn't use distilled water? Sulaiman - 20-11-2019 at 19:50
Living in a hard water area I use deionised water for all chemical reactions/solutions.Dr.Bob - 21-11-2019 at 18:06
I work in a real lab, and even there we use deionized water where it seems most useful, like reactions with metals, high value things, and analytical
work. For many functions, tap water is fine, like quenching reactions, large scale reactions, cooling condensers, and making brine solution. The
chlorine would be bad for many reactions with amines, alcohols, and other easily oxidized materials. And fluoride might be bad for silicon
compounds...
Well water might be very hard, but no chlorine, and maybe less fluoride. Deionized water may still contain some chlorine or other organics if not
coupled to carbon filtering or other purifications.S.C. Wack - 21-11-2019 at 19:11
pH can also be an issue with city water...I installed home RO. We use a big RO system at work.pantone159 - 21-11-2019 at 20:59
I use distilled water (from grocery store in 4L jugs) for all chemistry. I use small enough volumes that there is no reason not to. I keep my home
emergency water in these gallon jugs, and rotate them into the lab as needed. j_sum1 - 21-11-2019 at 21:27
I have my lab plumbed to a rainwater tank. It is very slightly acidic likemost rainwater but I do not know what the makeup of the dissolved acid is.
I doubt there is much in the way of ionic contamination although there may be a bit of organic or biological contamination. I use this for almost
everything: specifically cleaning and rinsing and have never had any problems. I do use bottled deionised water for anything analytical and anything
that might be sensitive to the contaminants that may be in the tank water. But this is actually quite rare.
The reality is that I am far more likely to pick up contamination from the ubiquitous dust that pervades my lab. This is high in iron from the soil
in these parts. I have noticed it in particular when working with strong acids in beakers that I have not checked properly.B(a)P - 22-11-2019 at 02:34
How close are you too the coast? Aerosol 'fall out' can become a big issue in my experience of you are close to the coast. Close, obviously depends on
local weather conditions.
I had always thought rainwater was low in pH because of dissolved CO2, is the wrong?Ubya - 22-11-2019 at 02:46
How close are you too the coast? Aerosol 'fall out' can become a big issue in my experience of you are close to the coast. Close, obviously depends on
local weather conditions.
I had always thought rainwater was low in pH because of dissolved CO2, is the wrong?
CO2, NO2, SO2, but yeah mostly CO2 if you don't live near an industrial zonej_sum1 - 22-11-2019 at 03:01
200km from the coast and out of reach of salt spray.
Rain is acidic from CO2, NO2 (lightning) and SO2 (fossil fuels and other sources). All of these could be present to some extent but CO2 is probably
most prevalent.
PH in my tank is greater than 6.5 and usually closer to 7 than I can measure accurately.draculic acid69 - 22-11-2019 at 05:41
I never worried about it until I moved to where I'm living now.the water here is full of what I think is chalk(calcium carbonate) the p.h. is still 7
but boiling a litre or two down leaves residue over everything and crystals start to precipitate.might be dolomite or some calcium/magnesium mineral
of some sort.after seeing this I'll be using distilled water for most things.sodium_stearate - 22-11-2019 at 09:09
For my process of making brown wax for casting
recording blanks for Edison cylinder phonographs,
I've found that using distilled water for everything
helps keep the surface noise down to an absolute minimum.
At one time, I'd use tap water to rinse the glassware between
process steps. After I changed over to distilled
water rinses, the blanks got noticeably quieter as far
as background surface noise.
I've always used distilled water when making up the
lye/water/aluminum solution which gets used to
saponify the stearic acid.
My take on this is that tap water always has
some dissolved minerals. That stuff will mess up
your desired end product. Tellurium - 22-11-2019 at 10:41
For reactions I'm using distilled water all the time, since it's very cheap(around 2$/5L in the supermarket) and I'm sure, that I don't bring any
unwanted Ions into my reaction.
However for cleaning glassware/cooling water I just take the water from the tap, the water where I live isn't that hard anyway.
But most of the time the reagents used cost way more, compared to the bit of water used, so I think it's better to spend a few cents on the water,
than taking a risk of messing up something or contaminating the productBedlasky - 22-11-2019 at 17:49
For test tube reactions I use tap water in most of cases. Here is soft water with high content of Fe which is fine for most inorganic reactions.
Sr2+, Ba2+, Ag+, CO32-, PO43-, C2O42-
give you some turbidity due to precipitate formation and SCN- give you pale orange-red solution due to complex formation - so for this
salts I use distilled water.
For preparations I sometimes used distilled water, sometimes tap water - it depends on how pure compound I need and on amount.
For analytical purposes I use distilled water.MrHomeScientist - 27-11-2019 at 10:34
My opinion: If you can eliminate variables by using distilled at just $1/gal, then why not? If there's an unexpected reaction, the last thing I'd want
to worry about is the quality of my water (plus it would be very hard to test for such trace contaminants).
I clean glassware in the sink, but always give a final rinse with distilled. This keeps everything ion-free and clean, and eliminates water spots.Lion850 - 27-11-2019 at 12:05
I buy Demineralised water from our local hardware chain. Distilled water is more expensive and not so conveniently available in 5 liter bulk.G-Coupled - 27-11-2019 at 14:32
I'm sure they used to sell distilled water in supermarkets and local shops so people in hard water areas could fill their steam irons and car
radiatiors back in the day, but I've not seen it since a long time ago. They used to sell it in shops in places with soft water, too.
I wonder when/why they stopped? Sulaiman - 27-11-2019 at 16:22
probably when they discovered the profit margin on little bottles of drinking water G-Coupled - 27-11-2019 at 16:36
lol, I would've thought they could both invent Perrier *and* keep selling very flat tasting distilled water in the 'car' section or whatever locally.
That's why I'm not the millionaire, I guess... draculic acid69 - 27-11-2019 at 16:49
I buy Demineralised water from our local hardware chain. Distilled water is more expensive and not so conveniently available in 5 liter bulk.
Demineralised water or deionised water from supermarkets and hardware stores around here is no good for chemistry stuff with whatever the shit in it
is.you take a sip of it and tell me that it's acceptable to use for what you would use tap water for.i tried it for a project and ended up with syrup
instead of salt.distilled or tap water only.draculic acid69 - 27-11-2019 at 16:56
I'm guessing the impurity is some rust inhibitor.CharlieA - 27-11-2019 at 17:04
My methods:
-for chemistry/biology/biochemistry stuff of any kind: distilled water (~$1/gal at grocery store; I'm too lazy to make my own: D)
-for drinking/mixed drinks: tap water
-for washing glassware: tap water
-for rinsing washed glassware: distilled water
When I worked in a laboratory at a civil engineering firm, we switched from 5-gal bottles of distilled water, to a commercial de-ionizing system: If I
remember correctly, the deionized water had negligible TDS and essentially zero conductivity, but using the dH2O instead of DH2O still offended my
professional sensibilities!
P.S. Happy Thanksgiving to all. -CG-Coupled - 27-11-2019 at 17:56
Wow - one buck a gallon for good stuff? That's insanely cheap. To buy 1L from the 'bay or Amazon can cost like 10 EUR. It's better deals at like
5L/10L and above, but nowhere near as cheap as that.
If I could buy distilled/deionized water anywhere near that cheaply, and especially locally, I'd use it for rxns exclusively. Bearing in mind how much
all the other reagents etc. cost, it'd be insane to cheap out on the water.
What differences, if m/any does anyone notice with distilled vs deionized water? Q
[Edited on 28-11-2019 by G-Coupled]
[Edited on 28-11-2019 by G-Coupled]beta4 - 28-11-2019 at 13:28
After some experiments a while ago, I've settled to using deionized water from supermarkets both for reactions and for the final rinse after washing
glassware. It's cheap enough and saves me from having to worry about water purity when some reaction doesn't work as expected.
For reference, the reactions I've performed that I consider most sensitive are the synthesis of phosphorescent materials (sensitive to Fe ions down to
ppm range), and Pd-catalyzed copper plating on nonconductive materials.
For the condenser water when running distillations, I use regular tap water circulated through a pump. It's cheaper but I'm seeing scale buildup in
the water reservoir.
[Edited on 28-11-2019 by beta4]G-Coupled - 28-11-2019 at 14:29
Shouldn't be too difficult to remove hard water scale from glassware so long as it's not allowed to massively build up and to really cake on AFAIK.
Is the Fe acting as an activator or sorts or a poison in the case of the phosphorescent stuff? CharlieA - 28-11-2019 at 19:17
Yes, $1USD/gallon is relatively cheap. Of course, you can always make your own distilled water. If I had to make my own I know I would be less
wasteful. I'm sure it would help me decide to go with smaller scales.beta4 - 29-11-2019 at 11:48
Shouldn't be too difficult to remove hard water scale from glassware so long as it's not allowed to massively build up and to really cake on AFAIK.
Is the Fe acting as an activator or sorts or a poison in the case of the phosphorescent stuff?
My water reservoir for cooling the condenser during distillations is just a plastic jug, so I don't care much about scale formation in it. My concern
is that scale is likely forming also in the water pump. I'm wondering if running the pump for some time with a mildly acidic solution would dissolve
it. Someday I'll try with the jug first as a test, and if it turns out cleaner I'll try with the pump too.
From my understanding - in doped ZnS phosphors at least - Fe impurities create locations in the crystal which allow excited electrons to return to
their ground state without emitting photons, thus reducing brightness significantly even at very low concentration.
G-Coupled - 29-11-2019 at 11:54
So, the Fe poisons the phenomenon which produces the phosphorescence effect? That's interesting.
Even a weak Acetic Acid solution should suffice to get rid of limescale pretty gently AFAIK. chemist1243 - 30-11-2019 at 16:42
it does not matter unless the procedure specifically states that you use distilled water.G-Coupled - 30-11-2019 at 16:45
