I recently found data pertaining to the pH level of certain
concentrations of NaOH. Specifically, 0.01 N of NaOH is suppose to be
at a pH of 12. Seems like this would be a way to standardize the
solution. Does anyone in this group know why this isn't common
practice?

tia
clyde

I am not sure whay you mean?

Do you mean that if you take the pH of your solution it shoudl read 12
on teh pH meter if it is correct?

Yeah, you coudl do this, butin practice pH meters are not precise
enough to do that. (Precision in chemisty is the ability of the
technique to determine the EXACT value). Standardization with
potassium hydrogen phthalate is the simplest method for accurate
determinization of the true concentration of Sodium hydroxide.

the reason for this is that crystaline sodium hydroxide is highly
hygroscopic. It picks up water from the air very easily. So it is
difficult to determine if you really have the measured amount of NaOH.


Now with all that being said, as home winemakers you really do not need
to be that accurate. The types of errors you will see maybe on the
order of 0.05% TA or so and will really not make a huge difference in
your wine.

Thanx for your reply Droopy.

That is what I meant as far as reading the concentration of NaOH with a
pH meter. And the inaccuracy of such a procedure is what I suspected,
though in practice, it does seem to be fairly feasible with a
resolution of two decimals on a meter.

I don't make up solutions from crystals, namely because of what you
stated about the hygroscopic properties, and partly because I don't
trust my ability to weigh things that accurately. Instead, I purchase
1 N stock and dilute it down. Measuring volumes accurately seems
fairly straight forward, though now I'm beginning to question the
distilled water purchased locally. I standardize my solutions often
due to the degradation characteristics of NaOH in solution plus the
question mark surrounding the distilled water.

And finally, I'm not a homewinemaker. Not much beyond that, but do
produce over 10k gallons professionally.

regards,

clyde

p.s. I use to post to this group frequently, and at that time there
were other professionals here including many that where as qualified as
professionals, but our ISP dropped the usenet account. Google use to
be a hassle to use, but seems be acting well now!?

I would look into standardization with KHP then. Basically yuou bake
the kHP in a warm oven to dry it out. Weigh it out, take it up into
solution and titrate it with your NaOH solution. Then you can
calculate your NaOH concentration. It is a proceedure used in college
chemistry classes so you should be able to find the exact proceedure on
google.

The problem is your 1 N NaOH solution will go bad just as easily as
your 0.1 N solution. As far as water to use, deionized water should be
fine but you have to degas it before use. To degas all you need to do
is boil the water for 5-10 min. Alternately you can vacuum degas it.
You have to do that to get rid of any CO2 dissolved in the water. (the
CO2 is what degrades NaOH, they combine to form bicarbonates).

wrote:
I recently found data pertaining to the pH level of certain
concentrations of NaOH. Specifically, 0.01 N of NaOH is suppose to be
at a pH of 12. Seems like this would be a way to standardize the
solution. Does anyone in this group know why this isn't common
practice?

tia
clyde

I can't remember off the top of my head but there is some other thing -
potassium phtalate maybe? - that's used to standardize AFAIK. Iverson
talks about it in his book.

BUT - why wouldn't this work - make a solution of say 10g TA in 1L
distilled water and titrate that. The error from 10g/L TA should give
the adjustment to the measured TA value in wine with this solution, no?
Or does it matter that one solution is water and the other wine?

Pp

The following procedure published by vinquiry, using HCL, is the one
I've been using for years;

http://vinquiry.com/pdf/reagentstandardQ.pdf

For the few months that it resides on my shelf, 1N NaOH is plenty
stable. I always standardize after making up the various
concentrations, so I'm quite certain of this. Yesterday I ran across
data on the net for the pH levels of the various concentrations, and
they seemed to be predictable with the readings I was getting from the
above procedures. Just made me wonder.

And, for he record, this concentration of NaOH (0.01) is being used for
an A/O test, so the results are a bit more important to me than those
for TA.

thanx again for your comments,

clyde

"pp" wrote in message
ups.com...

wrote:
I recently found data pertaining to the pH level of certain
concentrations of NaOH. Specifically, 0.01 N of NaOH is suppose to be
at a pH of 12. Seems like this would be a way to standardize the
solution. Does anyone in this group know why this isn't common
practice?

tia
clyde

I can't remember off the top of my head but there is some other thing -
potassium phtalate maybe? - that's used to standardize AFAIK. Iverson
talks about it in his book.

Potassium hydrogen phthalate is what you're thinking of. The reasons it's
used as an acid standard a
(1) It has a very low % of reactive (titrable) hydrogen,
(2) It's easily prepared in high purity,
(3) It's very stable.

BUT - why wouldn't this work - make a solution of say 10g TA in 1L
distilled water and titrate that. The error from 10g/L TA should give
the adjustment to the measured TA value in wine with this solution, no?
Or does it matter that one solution is water and the other wine?

Using tartaric acid as a standard for determining the titer of your NaOH is
probably good enough - at least for TA measurements. It won't give you
"gnat's ass" accuracy, but you really don't need that for most practical
winemaking purposes.

Tom S
www.chateauburbank.com

"pp" wrote in message
ups.com...

wrote:
I recently found data pertaining to the pH level of certain
concentrations of NaOH. Specifically, 0.01 N of NaOH is suppose to be
at a pH of 12. Seems like this would be a way to standardize the
solution. Does anyone in this group know why this isn't common
practice?

Mainly because that isn't a very precise method. In fact, it's barely in
the ballpark.

I'd guess that 0.05N and 0.015N NaOH solutions are pretty close to that
same pH, so the slope of the pH meter's response between them would be quite
shallow, despite the swing being a ±50% deviation from the norm.

Your pH meter would have to be a lot more sensitive, displaying accurately
and at a much higher resolution, _repeatably and constantly_, than it is
capable of doing to be useful in this fashion.

Tom S
www.chateauburbank.com.

Tom S ) wrote:
"pp" wrote in message
oups.com...

wrote:
I recently found data pertaining to the pH level of certain
concentrations of NaOH. Specifically, 0.01 N of NaOH is suppose to be
at a pH of 12. Seems like this would be a way to standardize the
solution. Does anyone in this group know why this isn't common
practice?

tia
clyde

I can't remember off the top of my head but there is some other thing -
potassium phtalate maybe? - that's used to standardize AFAIK. Iverson
talks about it in his book.

Potassium hydrogen phthalate is what you're thinking of. The reasons it's
used as an acid standard a
(1) It has a very low % of reactive (titrable) hydrogen,
(2) It's easily prepared in high purity,
(3) It's very stable.

BUT - why wouldn't this work - make a solution of say 10g TA in 1L
distilled water and titrate that. The error from 10g/L TA should give
the adjustment to the measured TA value in wine with this solution, no?
Or does it matter that one solution is water and the other wine?

Using tartaric acid as a standard for determining the titer of your NaOH is
probably good enough - at least for TA measurements. It won't give you
"gnat's ass" accuracy, but you really don't need that for most practical
winemaking purposes.

Tom S
www.chateauburbank.com


Hey,

does nyone but me find that their potassium hydrogen phthalate gets
pretty moldy pretty quickly? I've started storing it in the
fridge--how do other people store theirs?

Thanks!

--
Dave
************************************************** **************************
Dave Breeden

Thanx Droopy; TomS,

I supsected as much. My readings must have just been lucky.... I
didn't really check many different concentrations.

clyde

"David C Breeden" wrote in message
...
Hey,

does anyone but me find that their potassium hydrogen phthalate gets
pretty moldy pretty quickly? I've started storing it in the
fridge--how do other people store theirs?

Baking at ~250°F for an hour or so (to drive off water and kill any mold
spores) and keeping it in a tightly sealed glass bottle should stop that
problem.

Tom S
www.chateauburbank.com

Tom S ) wrote:
"David C Breeden" wrote in message
...
Hey,

does anyone but me find that their potassium hydrogen phthalate gets
pretty moldy pretty quickly? I've started storing it in the
fridge--how do other people store theirs?

Baking at ~250°F for an hour or so (to drive off water and kill any mold
spores) and keeping it in a tightly sealed glass bottle should stop that
problem.

Tom S
www.chateauburbank.com


No, no, sorry. I mean the *solution* gets cloudy pretty quickly,
not the powder.

Dave
************************************************** **************************
Dave Breeden

Yeah standardization with HCl would work, but it is far from analytical
in the sense of being highly precise.

Moldy?

That is weird. I have always seenit stored on the shelf and have never
seen any go bad.

I have seen bottles of this stuff sitting around on shelves for upwards
of 30 years (not personally seen, but have seen bottles that old).

If yours is gettng moldy, you should store it in a drier location....of
find a different supplier.

"David C Breeden" wrote in message
...
Tom S ) wrote:
"David C Breeden" wrote in message
...
Hey,

does anyone but me find that their potassium hydrogen phthalate gets
pretty moldy pretty quickly? I've started storing it in the
fridge--how do other people store theirs?

Baking at ~250°F for an hour or so (to drive off water and kill any mold
spores) and keeping it in a tightly sealed glass bottle should stop that
problem.

Tom S
www.chateauburbank.com


No, no, sorry. I mean the *solution* gets cloudy pretty quickly,
not the powder.

KHP is not normally used in liquid form as a standard - probably at least
partially for that very reason, but mainly because the titer will shift
somewhat with age/use, thereby reducing its value as a precise standard.

Best to use the dry powder for standardizing.

Tom S
www.chateauburbank.com