Calling all would be scientest

[Stressbaby]

I got a small task you could do. Should not take more than 20 minutes. Wana give it a go?

Sure if you don't have a deadline.

 

[seth8530]

I feel like the best way moving forward is for one of us to take 100 ml of water. Add 3 grams of sugar to it. ( should give you 1.010) Then add 60 ml of 40% abv spirit to give you a solution at 15% abv. This will give you a total volume of 160ml. which give you 3 grams of sugar per .160 liters.

This is the same as 18.75 grams of sugar per liter.

Which if you look at this chart http://www.brsquared.org/wine/CalcInfo/HydSugAl.htm

Should put you right at 1.005 or more precisely 1.00561 if you were to perform a linear interpolation on that chart.


If you wonder how I got my numbers


I set

.15=W*.4/(100+W) Where W is the volume of spirit needed, .4 is the abv of the spirit, (100+W) is the volume of the spirit and sugar water and .15 is the wanted abv.

Now what we would be looking for is how far below 1.005 does the spirit put the mixture at. If it is extremely close then this whole issue is no big deal. If it is off by a larger certain percentage, then things are more interesting. I do not have a hydrometer or scale handy so I cant perform this experiment.

Make sure to make temperature corrections to the hydrometer!

Thanks a ton!

 

[DoctorCAD]

I think the best "test" method would be to take pure RO and distilled water, an exact amount, and add pure and filtered alcohol until you have the mix you are looking for, say 13%.

Take an exact amount of that solution and weigh it (and I'm talking a Mettler balance or other high-end system) accurate to 4 decimal places. Take the same amount of wine, known to be 13% and weigh that as well. The difference would be the weight of all of the TDS.

Those solids are what makes your experiment difficult, if not impossible, because (I'm guessing) every wine type would have a different amount of those solids. The solids help "float" the hydrometer, causing ABV calculations to be off.

All of your calculations and experiments are basing the outcomes on "clear" liquids and wine is not clear.

 

[JohnT]

I have a better idea. Forget APV.

.01% apv has almost no effect on the human body. Products can have "alcohol free" on the label, and still have a level of .01 apv.

I say that we measure the FF (aka "the Fershnickered Factor").

This is the number of glasses (with respect to time) that it takes to get "faced".

 

[cmason1957]

I stumbled across some interesting pages about this subject (searching for something else). This one gives five different formulas to calculate the Potential Alcohol. With a note that one of them seems to give close ebulliscope: http://www.brsquared.org/wine/CalcInfo/HydSugAl.htm (this may have been posted earlier).

This one is posted on a Beer making site, but says the more complicated formula seems to provide greater accuracy at the higher gravities used for wine making:
http://www.brewersfriend.com/2011/06/16/alcohol-by-volume-calculator-updated/

The more complicated formula is AVB = (76.08*(SG-FG)/(1.775-SG)) * (fg/0.794)
http://www.brewersfriend.com/2011/06/16/alcohol-by-volume-calculator-updated/

 

[FABulousWines]

I agree with John. If I can get an estimate close to 0.5% that is good enough for home wine making/drinking. All I really care about is keeping the ABV between 10% and 13%. Hot enough to remain stable, but not so hot that it overwhelms the taste.

But, Seth, I do admire your efforts. I wish more of my employees had your work ethic!

 

[Flugel91_30]

Well, technically speaking, the second equation's value (1.05/.79) is the K value you are looking for. This constant essentially tries to relate the volume of alcohol in the mixture to its density, adjusting the variables (specific gravity) appropriately. Other than relating alcohol to CO2 (I see the connection, I just don't see why they're using it in this equation because after degassing, density should be irrespective of CO2 produced), I think this is a fairly good value to use. However, if I were you, I wouldn't use "K," as in chemistry "K" most often stands for Kelvin or, in the lower case, a rate or equilibrium constant for a chemical reaction. Just my 2 cents there, though.

Essentially, the value (SG-FG)/FG relates the change in specific gravity, or density relative to water, as a decimal percentage. Multiplying by 100 turns this into a more familiar percent change value (percentage). This equation uses density, however, and not molarity or some other total mass measurement, and so can only really approximate the total sugar and thus % abv.

An equation using degrees Brix would hypothetically be more accurate, as this is a % by weight measure. Say, for instance, you have 5 gallons of must, pre-ferment, at 22.5 degrees brix. Since 1 degree Brix is 1 gram of sucrose per 100 grams of water, you have 22.5 grams of sucrose, or roughly 45 grams of glucose (1 sucrose = 2 glucose dimerized), per 100 grams of water. We have 5 gallons of must, and since 1 gallon=3.785 Liters = 3785 grams of water, we have a total sugar mass of ((22.5g/100g) x 3785g) x 5 = 4258 g sucrose, or 9.38 pounds of sucrose. This is, in turn, equal to 12.44 moles of sucrose.

If we proceed to a FG of 1.000, with a degrees brix of 0.0, then all 12.44 moles of sucrose have, hypothetically, become CO2 and Ethanol. Since 1 mole of sucrose yields 4 moles of ethanol, we should now have 49.8 moles of ethanol. This is a molarity of 2.63 M, or 2.63 moles of ethanol per liter of solution. 2.63 moles of ethanol equals 121.g ethanol, which again is per 1L water or 1000g water, giving a percent by mass of 12.11%. To get % abv, you would have to convert this value, which I honestly do not know how to do. One would need to know the volume of the solution, which can really only be determined accurately by measuring.

I wouldn't consider this authoritative by any means. It's really just me tinkering with things stoichiometrically. I'm not a professional chemist, but have studied chemistry in college. Still, again don't consider this definitive. I'm sure I've made an error somewhere... This answer is fairly close, however, to the % abv you would get following the scales on a triple scale hydrometer (12.11% as opposed to 12.9%). This difference should be accounted for when converting to % by volume, though. I would honestly argue that % by mass is a better measure than % by volume, as % by mass doesn't change with temperature. Of course, you probably aren't serving wine in/at wildly fluctuating temperatures...

Anyway... that's a lot of calculations, enough to warrant my stopping for a while lol. As I've state elsewhere, I'm pretty new to wine-making. I do, however, know a little about chemistry...

 

[Flugel91_30]

I feel like the best way moving forward is for one of us to take 100 ml of water. Add 3 grams of sugar to it. ( should give you 1.010) Then add 60 ml of 40% abv spirit to give you a solution at 15% abv. This will give you a total volume of 160ml. which give you 3 grams of sugar per .160 liters.

This wouldn't provide 160 mL of solution, as adding solute and solvent produces a volume of solution that is actually less than that of the sum of the two volumes. This is because the solute, in a sense, 'meshes' with the solution. In other words, the solute molecules are interspersed in between the solvent molecules. It's kind of like pouring marbles into a ball pit; the marbles make up for a measurable increase in volume, but some fill the empty spaces between the balls and thus do not add to the total volume.

 

[Runningwolf]

Whoooa you guys are like a good mysterious wine. Who know's whats in it but is sure is good. I have no idea what the He!l you guys are saying but I'm impressed! I can't even think of any BS to give you this time.

 

[seth8530]

I stumbled across some interesting pages about this subject (searching for something else). This one gives five different formulas to calculate the Potential Alcohol. With a note that one of them seems to give close ebulliscope: http://www.brsquared.org/wine/CalcInfo/HydSugAl.htm (this may have been posted earlier).

This one is posted on a Beer making site, but says the more complicated formula seems to provide greater accuracy at the higher gravities used for wine making:
http://www.brewersfriend.com/2011/06/16/alcohol-by-volume-calculator-updated/

The more complicated formula is AVB = (76.08*(SG-FG)/(1.775-SG)) * (fg/0.794)
http://www.brewersfriend.com/2011/06/16/alcohol-by-volume-calculator-updated/

Thanks for the equations, I will give them a look!

Well, technically speaking, the second equation's value (1.05/.79) is the K value you are looking for. This constant essentially tries to relate the volume of alcohol in the mixture to its density, adjusting the variables (specific gravity) appropriately. Other than relating alcohol to CO2 (I see the connection, I just don't see why they're using it in this equation because after degassing, density should be irrespective of CO2 produced), I think this is a fairly good value to use. However, if I were you, I wouldn't use "K," as in chemistry "K" most often stands for Kelvin or, in the lower case, a rate or equilibrium constant for a chemical reaction. Just my 2 cents there, though.

Essentially, the value (SG-FG)/FG relates the change in specific gravity, or density relative to water, as a decimal percentage. Multiplying by 100 turns this into a more familiar percent change value (percentage). This equation uses density, however, and not molarity or some other total mass measurement, and so can only really approximate the total sugar and thus % abv.

An equation using degrees Brix would hypothetically be more accurate, as this is a % by weight measure. Say, for instance, you have 5 gallons of must, pre-ferment, at 22.5 degrees brix. Since 1 degree Brix is 1 gram of sucrose per 100 grams of water, you have 22.5 grams of sucrose, or roughly 45 grams of glucose (1 sucrose = 2 glucose dimerized), per 100 grams of water. We have 5 gallons of must, and since 1 gallon=3.785 Liters = 3785 grams of water, we have a total sugar mass of ((22.5g/100g) x 3785g) x 5 = 4258 g sucrose, or 9.38 pounds of sucrose. This is, in turn, equal to 12.44 moles of sucrose.

If we proceed to a FG of 1.000, with a degrees brix of 0.0, then all 12.44 moles of sucrose have, hypothetically, become CO2 and Ethanol. Since 1 mole of sucrose yields 4 moles of ethanol, we should now have 49.8 moles of ethanol. This is a molarity of 2.63 M, or 2.63 moles of ethanol per liter of solution. 2.63 moles of ethanol equals 121.g ethanol, which again is per 1L water or 1000g water, giving a percent by mass of 12.11%. To get % abv, you would have to convert this value, which I honestly do not know how to do. One would need to know the volume of the solution, which can really only be determined accurately by measuring.

I wouldn't consider this authoritative by any means. It's really just me tinkering with things stoichiometrically. I'm not a professional chemist, but have studied chemistry in college. Still, again don't consider this definitive. I'm sure I've made an error somewhere... This answer is fairly close, however, to the % abv you would get following the scales on a triple scale hydrometer (12.11% as opposed to 12.9%). This difference should be accounted for when converting to % by volume, though. I would honestly argue that % by mass is a better measure than % by volume, as % by mass doesn't change with temperature. Of course, you probably aren't serving wine in/at wildly fluctuating temperatures...

Anyway... that's a lot of calculations, enough to warrant my stopping for a while lol. As I've state elsewhere, I'm pretty new to wine-making. I do, however, know a little about chemistry...

I disagree with K being a bad constant since it is used in many other things other than chemistry ( about 15 million things in engineering) but that does not matter.. I do think that the equatin that is givin is not quite right because the units do not seem logical to me.

The important thing is that I agree with you, going through this in a stochiometric manner is the best way to do it. However, the whole reason why I care so much about getting the proper ending residual sugar is so that I can accurately apply the stoch to create a formula that uses this ending residual sugar that we are trying to create a SG correction for. So, I think we are on the same general train of thought.

This wouldn't provide 160 mL of solution, as adding solute and solvent produces a volume of solution that is actually less than that of the sum of the two volumes. This is because the solute, in a sense, 'meshes' with the solution. In other words, the solute molecules are interspersed in between the solvent molecules. It's kind of like pouring marbles into a ball pit; the marbles make up for a measurable increase in volume, but some fill the empty spaces between the balls and thus do not add to the total volume.

This is true, I was surprised when I found this out. However, I should not of been. Conservation of mass is a fact, conservation of volume is not. However, I think it is irrelevant for this test I am want performed because I am only looking for how badly the alcohol will affect the reading on the hydrometer.

Good thought tho!

 

[DoctorCAD]

Seth, flugel was not saying not to use a constant, rather he was referring to K vs. k.

Big K = degrees kelvin
small k = constant

 

[seth8530]

That is not the way I interpreted what he said. The way, I saw it he was disputing my use of that variable name because of possible confusion. However, like I said earlier names of variables are moot points. K, k, ,Ll, Allababba Wallakazoo, all fit just as fine so long as they are defined before hand.

 

[spaniel]

Interesting discussion.

Being a trained (although not practicing) scientist....cell and molecular biology, a handy education to transition into winemaking...I really try not to apply such rigor to a hobby. I go by the difference on the hydrometer, and declare it "close enough".

To determine the error, I would do the following. Say we are targeting a semi-sweet wine with a final SG of 1.010. So measure a sample of sugar water that reads 1.010...knowing the exact weight of sugar contained in that sample (start with distilled water, add sugar in weighed increments). Now, create a sample of equal volume with known ABV, containing the same weight of sugar. What is the difference in the SG reading? There is your error. Run the experiment and tell me the answer.

Now, this does not answer the question of the influence of other dissolved solids, which is a real concern. But from an academic standpoint it would isolate the error introduced by the alcohol. Truly, I am interested in the answer.

 

[seth8530]

Interesting discussion.

Being a trained (although not practicing) scientist....cell and molecular biology, a handy education to transition into winemaking...I really try not to apply such rigor to a hobby. I go by the difference on the hydrometer, and declare it "close enough".

To determine the error, I would do the following. Say we are targeting a semi-sweet wine with a final SG of 1.010. So measure a sample of sugar water that reads 1.010...knowing the exact weight of sugar contained in that sample (start with distilled water, add sugar in weighed increments). Now, create a sample of equal volume with known ABV, containing the same weight of sugar. What is the difference in the SG reading? There is your error. Run the experiment and tell me the answer.

Now, this does not answer the question of the influence of other dissolved solids, which is a real concern. But from an academic standpoint it would isolate the error introduced by the alcohol. Truly, I am interested in the answer.

That is pretty much what I was shooting for. However, I like your method! It is simple!

 

[Midwest Vintner]

You won't ever be that close with a hydrometer. It is not just solids (which will increase during fermentation if you are using any such as skins, etc), but also other fermentable solids that may or may not be in the sample or be turned into alcohol. For me, .5% abv is not going to change a whole lot. A huge part of the wine making process is knowing your taste buds, IMHO.

 

[seth8530]

You won't ever be that close with a hydrometer. It is not just solids (which will increase during fermentation if you are using any such as skins, etc), but also other fermentable solids that may or may not be in the sample or be turned into alcohol. For me, .5% abv is not going to change a whole lot. A huge part of the wine making process is knowing your taste buds, IMHO.

The issue is that we might be off more than .5%. We could be off my 2% for all we know (prob not that bad) but who knows? The goal I have is to create a physics driven ABV equation for us to use. I agree, it will not be perfect but I want us to do better and not perfect.

 

[BernardSmith]

@Seth, This discussion of accuracy (and reliability) is interesting. I may be wrong - (Ha! I often am) but I believe that the tolerance in law for a stated ABV is plus or minus 1.5 %, so a commercial winery claiming that their wine is 12.5% ABV might legally have produced a wine closer to 11 % or as high as 14 (http://blog.wblakegray.com/2013/05/note-to-wineries-label-alcohol.html) ... In other words, for practical purposes , the law allows a range of 3 percent

 

[seth8530]

Thanks! You are correct that their is a legally given tolerance. I think the allowed error in TN is +- 1 percent abv.

 

[seth8530]

Thanks everyone for the input! I have decided that for the new ABV equation it will most likely be best to first solve it in terms of mass of alcohol. This will help us out because chemical reactions are done in terms of mass not volume.

If we can find out a residual sugar correction for a hydrometer we can use that to determine the amount of sugar that was consumed in the chemical reaction and thus get the mass of alcohol in the solution. Once that has been done we can use an equation that I managed to derive today that will take us from mass of alcohol into ABV.

Please, I am asking anyone who can to look over my math to make sure it looks good. I have been known to make mistakes from time to time.

So items that we need to make this work

- A correction factor that relates the final gravity to the actual sugar content of the wine

- An equation that relates the change in sugar to the mass of alcohol created in the wine.

If we can get these we will have a physics based ABV equation.

PLEASE EXCUSE MY HANDWRITING!

View attachment Derivation of ABW to ABV.pdf

 

[cmason1957]

The math seems to be straight-forward enough algebra.

The items which need work seem to be the big problem here.

I was worried, when I first read your post that there might be real math in there. I was almost expecting differentials or integrals, or at least a summation.