I started getting inconsistent results with this device. My hunch is that the seals aren’t airtight anymore, and I’ve been meaning to replace some of the parts (hoses, syringe, and maybe the bung). Haven’t gotten to that yet. It’s on the list!

Erroll

An acid, any acid, is a molecule that can break into one (or more) hydrogen ion(s) and the rest of the molecule. A hydrogen ion is just a free proton, and that’s why acids are sometimes described as “proton donors.”

When sodium bicarbonate is in a solution with an acid, the sodium (NA) combines with “the rest” to form a salt, and the bicarbonate (HCO3) combines with the hydrogen ion to form carbonic acid (H2CO3). The carbonic acid then breaks down into carbon dioxide gas (CO2 – which is what the acid testing device measures) and water (H2O).

This works for tartaric acid, citric acid, malic acid, and any other acid. Hope this helps,

Erroll

Thank you for the kind words!

I’ve been meaning to go into detail about how the device works, but I’ve been getting inconsistent results when I try to determine TA by measuring CO2. Also, other aspects of life have been demanding my attention, and I haven’t been able to devote as much time to the hobby as I would like. I expect this will change, and when it does, I’ll revisit the acid test device.

Please explain in more detail the *process* of using the titrating device in the photo. How do you take the readings and then how do you convert the raw data into usable information?

Thanks!

That’s a common formula, and it’s meant to simplify things. Really! It’s meant to be used by just plugging in your own numbers without thinking about what each term in the formula means.

Let’s say you’re using 0.1N sodium hydroxide (the normality should be printed right on the label), and you keep adding it to a 100 ml sample of wine until you reach the endpoint of your titration. Plugging some numbers into the formula:

TA = ( (ml sodium hydroxide) * 0.1 * 75 * 100 ) / ( 1000 * 100 )
= ( (ml sodium hydroxide) * 750 ) / 100,000
= (ml sodium hydroxide) * 0.0075

I don’t remember, off the top of my head, where the 75 comes from (I learned chemistry two decades ago). If you know the normality and volume of sodium hydroxide, you should be able to determine the amount (in moles) of tartaric acid. That plus the molecular weight should get you the mass of tartaric acid. I think the 75 is the result of multiplying some of those constants together. I’m afraid I’ll just get into trouble if I try to go into more detail than that.

The short answer is, you can use the formula literally. Just plug in your own numbers. It’s important to pay attention to your units – if it asks for ml give it ml, and remember that it’s giving you g/100 ml. So if you want g/L, multiply by 10.

Hope this helps,
Erroll

What on earth does the (75) mean in the equation?

PS I love the machine you made, market it, looks much easier to use than this math…………thanks

Ah, my tomato wine! When I last looked in on it, I described it as “young, tart, and bone dry.” That was back in February. I plan to taste and test it again, neutralize some of the acid, and age it some more. So I’m not done yet, and this story may have a happy ending.

But at this point, I can’t recommend it for general use – tinkerers and experimenters only! To them, I would say watch your acid. Consider not adding any up front then measure and adjust after the wine has fermented out. Above all, keep in touch so we can compare notes.

Erroll

I do intend to follow up with more on how to use it and how its made.

Erroll