Wayne Harris wrote:

> On Mar 9, 7:34Â*pm, "Lou" > wrote:
>> Hello Dick,
>> My Analytical chemist gave my NaOH from 2006 and said it will be fairly
>> close to .1N. It shouldn't make a big difference cause wine makers are
>> going for a range anyway. Hope he is not wrong!
>>
>> "Dick Heckman" > wrote in message
>>
>> ...
>>
>>
>>
>> > This brings up a related question. Â*How long is NaOH solution good for?
>>
>> > Dick
>>
>> > Paul E. Lehmann wrote:
>> >> Wayne Harris wrote:
>>
>> >>> On Mar 6, 2:13 pm, "Paul E. Lehmann" >
>> >>> wrote:
>> >>>> Lou wrote:
>> >>>>> I am going to run a titration with my burette using .1N NaOH to a
>> >>>>> Phenophtalene endpoint but have lost the equation to calculate the
>> >>>>> % tartaric acid. Despite my books and web articles I can't find it.
>> >>>>> Anybody have it written down? You know what I mean: x ml's of wine
>> >>>>> require x ml's of .1 NaOH equals the tartaric acid level. I also
>> >>>>> guide my adjustments with pH ( when I can get a sample to the lab
>> >>>>> at my job) and Taste of course. Thanks, Lou.
>> >>>> For a 5 ml sample of wine:
>> >>>> multiply the cc of .1N NaOh by 0.15
>>
>> >>>> Example:
>> >>>> 4.8 ml of NaOh x 0.15 = 0.72%
>>
>> >>>> Note:
>>
>> >>>> "For a red wine do not immediately add the phenolphthalein indicator
>> >>>> as you would with a white wine or must. Â*The red pigments make it
>> >>>> difficult
>> >>>> to see the end point unless you first titrate without
>> >>>> phenolphthalein until the color turns the red to a blue of green.
>> >>>> Only then will you add
>> >>>> the indicator and then continue to the first pink that persists. Â*If
>> >>>> the
>> >>>> sample is deeply pigmented you can dilute it with more distilled
>> >>>> water which does not affect the result."
>>
>> >>>> The above information from Presque Isle Wine Cellars
>>
>> >>>> I can give you their method to standardize sodium hydroxide with
>> >>>> potassium acid phthalate if you have some old NaOh and want to make
>> >>>> sure
>> >>>> it is still full strength and how to standardize if it is not.
>>
>> >>> I use this site:
>> >>>http://web2.airmail.net/sgross/fermc...lc_applet.html
>>
>> >> Good site. Â*In addition I think it is a good idea to have the formulae
>> >> in the cellar along with pencil and paper since not all of us have a
>> >> computer
>> >> there. Â*Also computers do fail - most often when you really need them.
>> >> Â*I have found out also, there is no substitute for a hard cover note
>> >> book and
>> >> make notes on paper. They can later be entered into your computer. Â*I
>> >> guess
>> >> I am a little old fashion is some ways.- Hide quoted text -
>>
>> - Show quoted text -
> So, I have a 25ml burette that I keep on a ring stand that I use for
> my titrations. This burette is usually full of NaOH. Will NaOH
> "keep" if kept in an open container like that?

The best thing to do is have Presque Isle (piwine.com) send you the
procedure for checking your NaOH. If it is weaker, you have the
information to use to adjust the calculations. This works for open or
closed containers of NaOH. If you had it stored in a closed container, it
does not mean it is full strength.