Thanks. I finally figured it out. I was using 5ml sample and getting
weird results. I increased to 15ml per other sites and the numbers came
out where they should.

I was going off of directions for using 0,1N, but using 0.2N and was
getting confused.

Still learning about all of this.

My sangiovese is finally where it should be.

The rest are a little low.
Chianti TA 5.5, pH 3.57, Pinot Nior TA 4.5 pH 3.6+.



Tom S wrote:
> "Marty Phee" > wrote in message
> . com...
>> I have 1/5N NaOH. If I use it to test acid using a ph meter do I double
>> the reading?
>>
>> I plan on buying some 1/10, but for the time being...
>
> No need to buy 0.1N when you have 0.2N on hand. Either use what you have
> directly and double the volume reading or dilute it 1:1 and use that.
>
> Fortunately, TA measurements aren't that terribly critical. Accuracy to ±
> 0.5 g/100 ml is good enough for winemaking purposes. You should be able to
> do that well, despite the fact that your NaOH standard will slowly change
> over time as it absorbs atmospheric CO2. :^/
>
> If you _really_ needed an an accurate result you'd want to standardize the
> NaOH solution against 3 or 4 carefully dried and weighed (to the nearest
> 0.0001 g) samples of potassium hydrogen phthalate (measuring the NaOH to the
> nearest 0.01 ml) and average the results. I did this in chem lab in college
> many years ago. It's tedious, but teaches one good technique and
> discipline.
>
> Tom S
> www.chateauburbank.com
>
>