pH of Distilled water
Woody Sturges
came out at around 5.2 or so (at around 68 degrees F). I assumed that
the pH was supposed to be 7.0, and that there were NO minerals, etc. By
getting a reading that low, can I assume that there are various minerals
in there? Are there normally variances like this?
Just checking,
Woody
Tom Biasi
If you got a 5.2 from distilled water either your water is contaminated or
you pH tester is way off. Your assumption is correct. The distilled water
should be 7.0 pH.
Check your bottle carefully, sometimes spring water is located near
distilled water and the labels look similar. ( No insult intended, I have
made that mistake when not using my reading glasses. )
Good Luck,
Tom
Woody Sturges wrote in message <383C49E9...@tranquility.net>...
Erik_Bloodaxe
>
> I did a pH check on a bottle of distilled water I just bought and it
> came out at around 5.2 or so (at around 68 degrees F). I assumed that
> the pH was supposed to be 7.0, and that there were NO minerals, etc. By
> getting a reading that low, can I assume that there are various minerals
> in there? Are there normally variances like this?
>
> Just checking,
> Woody
Ok, well, the water in the bottle may not be exactly distilled. It
might be Deionized water. In which case, your pH will be different,
depending on what type of deionization process is used. There are
demineralizers which remove the chlorides from the water, but leave
other impurities, depending on the chemical composition. This usually
leads to a basic pH though. There is also a chemical process where the
water is treated with different chemicals to remove the chlorides, which
then is filtered. This process, as I recall, will give an acidic pH.
Also, the temperature of the water affects the pH reading, giving you a
false indication. Generally the lower the water temperature below 77F
the lower the pH. Most commercially available pH cells will have some
kind of temperature compensation.
hhj
However, Pure water has no buffering capacity. When you expose it to Air,
CO2 is absobed into the water and this will lower the pH. You can not use
an unbuffered solution to calibrate your pH meter.
Erik_Bloodaxe wrote in message <383C5F34...@yahoodle.com>...
Darren Miller
will lower the pH to this level. Left exposed to the air the pH may drop
as low as 5.0.
just my two aussie cents worth
Tom Biasi
I know the pH of distilled water can be brought down to about 4.5 by
bubbling CO2 through it at atmospheric pressure and room temperature but can
the water absorb that much just sitting open in a room? I always leave my
water capped until use so I don't have this problem but I was just
wondering.
Cheers,
Tom
Darren Miller wrote in message <383C9447...@adelaide.edu.au>...
Mike Uchima
>
> I did a pH check on a bottle of distilled water I just bought and it
> came out at around 5.2 or so (at around 68 degrees F). I assumed that
> the pH was supposed to be 7.0, and that there were NO minerals, etc. By
> getting a reading that low, can I assume that there are various minerals
> in there? Are there normally variances like this?
>
> Just checking,
> Woody
When CO2 dissolves in water, it forms carbonic acid. Distilled water
will absorb a small amount of CO2 from the air; since distilled water
has no buffering capacity, even this small amount of dissolved CO2 will
lower the pH quite a bit. Try boiling some of it (to drive off the
CO2), quickly cooling it (but don't agitate it, or you'll re-dissolve
CO2 in it), and measure the pH again. It should be a lot closer to 7.0.
--
== Mike Uchima == uch...@pobox.com ==
Darren Miller
of microbiology. I too was suprised to see that the pH of the highest
purity water is acidic. It is due to the partial pressure of CO2 in the
air. Pure water has no buffering capability. The only way to keep it at
neutral pH is to cap the bttle immediately it is produced. You must then
use all of it in one go or the head of CO2 in the bottle will very
quickly reduce the pH. You can bet the people who bottle distilled water
distil it and store it in a tank before bottling as it a fairly slow
process.
Ken Hill
the pH of extremely pure water is notoriously difficult, because pure
water has a very low electrical conductivity. Also, as previously noted,
water exposed to air will rapidly absorb carbon dioxide, which lowers the
pH. So I would not see any cause for alarm in a pH 6.0 measurement for
purified water, whether RO, deionized, or distilled.
--
Ken Hill Derry, New Hampshire, USA
ken_...@ne.mediaone.net ICQ 2236887
"Swallow a live frog first thing in the morning,
and nothing worse will happen to you all day."
Victor M. Torrey Jr.
and getting PH measurements around 6.0. I then tried getting RO water
from another store with the same results. A call to the folks that own
the RO equipment yielded no answer.
I was assuming RO water would have a PH of 7 and I was concerned that
somehow their water was contaminated. When I received the same results
from a different location (same company), I started to wonder about the
process they were using.
Vic
brian grella
going to assume that you used pH paper. pH paper will give you a low
reading (acidic) due to the lack of buffering capacity. Their are no
solutes in the water to cause the paper to behave correctly. Try using a
pH meter.
Brian
Woody Sturges wrote in message <383C49E9...@tranquility.net>...
brian grella
willing to bet that it would take a lot.
Ken Hill wrote in message ...
Erik_Bloodaxe
>
> Water will have a pH of 7.0 when it is only water in the test tube.
> However, Pure water has no buffering capacity. When you expose it to Air,
> CO2 is absobed into the water and this will lower the pH.
Ah, yes, I had forgotten about the Carbonic acid formation.
You can not use
> an unbuffered solution to calibrate your pH meter.
>
> Erik_Bloodaxe wrote in message <383C5F34...@yahoodle.com>...
> >Woody Sturges wrote:
> >>
nobody
CO2) in the water, if you were to boil the water and then take a pH reading,
the reading should be around 7.
brian grella wrote:
> What did you use to make your pH measurement pH paper? or pH meter? I am
> going to assume that you used pH paper. pH paper will give you a low
> reading (acidic) due to the lack of buffering capacity. Their are no
> solutes in the water to cause the paper to behave correctly. Try using a
> pH meter.
>
> Brian
>
> Woody Sturges wrote in message <383C49E9...@tranquility.net>...