I am really confused about PH / TA now

[winemaker_3352]

Yes, if you are using a pH meter, it is good to get the level (volume) up a little, so the electrodes are submerged..

Yes I am using the Vinemetrica SC200 PH/TA meter.

Is there a reason why we can't use a larger volume of wine?

 

[ibglowin]

Using a larger volume of wine does 2 things.

1) waste more (precious) wine

2) waste more chemicals

And yes the reason you add distilled water is to have the electrode fully immersed in the solution.

 

[robie]

Using a larger volume of wine does 2 things.

1) waste more (precious) wine

2) waste more chemicals

And yes the reason you add distilled water is to have the electrode fully immersed in the solution.

And if you just add more wine, the calculations change, right, Mike?

 

[winemaker_3352]

And if you just add more wine, the calculations change, right, Mike?

That's what I thinking as well - but wanted to ask to make sure..

 

[ibglowin]

Yes since the volume has changed.

Here is the Equation for using any sample size and any strength NaOH.

TA as tartaric acid (g/100 ml) = (V) x (N) x (75) x (100) / (1000 x (v))


V = ml of sodium hydroxide solution used for titration
N = Normality of sodium hydroxide solution
v = sample volume (ml)

 

[winemaker_3352]

Thanks Mike.

Does the distilled water dilute the sample - water it down? Won't that affect the test results??

 

[ibglowin]

No, your measuring acid, distilled water has no acid so to speak. It will pick up some Carbonic Acid (from CO2 in the air) but its minimal. If you really want an accurate test, titrate your distilled water to pH 8.2 and then add your wine to that corrected water, then titrate as normal.

 

[robie]

Yes since the volume has changed.

Here is the Equation for using any sample size and any strength NaOH.

TA as tartaric acid (g/100 ml) = (V) x (N) x (75) x (100) / (1000 x (v))


V = ml of sodium hydroxide solution used for titration
N = Normality of sodium hydroxide solution
v = sample volume (ml)

This formula should be added to the tutorial section. Very clear!
Thanks, Mike