# ATTN Beer drinkers: What is the specific gravity of the wine and the percent alcohol content by volume?

Here is the question, it deals with specific gravity of alcohol and sugar:

Hydrometers are used in the wine and beer industries to measure the alcohol content of the product. This is accomplished by measuring the specific gravity of the liquid before fermntation, during fermentation, or after fermentation is complete. during fermentation, glucose is converted to ethyl alcohol and carbon dioxide gas, which escapes from the vat.

Brewer's yeast tolerates alcohol contents to approximately 5% before fermentation stops, whereas wine yeast tolerates alcohol contents ukp to 21% depending on the yeast strain. The specific gravity of alcohol is 0.8 and the maximum specific gravity of sugar in solution is 1.59. If a wine has a specific gravity of 1.08 before fermentation and all the sugar is converted to alcohol, what will be the final specific gravity of the wine and the percent alcohol content by volume? Assume the initial liquid contains only sugar and water.

Thanks for the help!

Relevance
• Anonymous

Solubility glucose = 91g/100mL [1]

maximum spec grav is 1.59 ours is 1.08 it must be 8/59ths of saturated

8 / 59 * 91g/100mL = 12.34g/100mL

Assume 1L = 1000g of water in mother liquor.

123.4g of glucose C6H12O6 to ferment.

123.4g glucose / 180g/mol glucose = 0.686mol glucose

C6H12O6 -> 2CO2 + 2C25OH

so you'd get 1.37mol EtOH which would weigh:

1.37mol * 34g/mol EtOH = 46.6g EtOH

And have a volume of:

1mL/g water / 0.8mL/g EtOH * 46.6g EtOH = 58.27mL EtOH

Total volume of solution is 1058.27 mL

58.27 / 1058.27 = 0.055 ratio of alcohol/water

*100 = 5.5%V/V alcohol

46.6 g EtOH + 1000g Water = 1046.6g Wine

1046.6g wine / 1058.27mL wine = 0.99 sp. gr.

When we refer to sugar in brewing, we are usually refering to sucrose, which is a disaccharide. So every sucrose gives us 4 ethanols. It is also more appropriate to use degrees Plato rather than points of gravity when describing OG. The conversion is a simple quadratic fit, meaning %weight of sucrose vs gravity is NOT a linear relationship!

80 points corresponds to 19.3 %w/w.

The rest is Stoichiometry

Assuming 100g of wort:

19.3 gSucrose * molS / 342gS * 4 molEtOH / 1molS *46 gEtOH / mol = 10.38 gEtOH. (assuming 100% attenuation).

10.38 gEtOH * 1mL / 0.8 gEtOH = 12.975 mL EtOH

12.975 mL EtOH / (12.975 ml EtOH + 80.7 mL H2O) = 14.6% ACV

(10.38 g EtOH + 80.7 g H20) / (12.975 mL EtOH + 80.7 mL H2O) = 1.023 g/mL (23 points final gravity)

This is a good starting point, but it is worth noting that this is just an estimate. For sugars other than sucrose, the %weight sugar in the wort will actually be higher than 19.3%, meaning more alcohol. To get a more precise answer, you need to know what sugars are in the wort, and which are fermentable. It is usually more useful to measure the OG and FG, then calculate your attentuation and ACV from those numbers.

• 3 years ago

It merely relies upon on the time of the twelve months and on the occassion. I drink alcohol and all varieties. i will have a corona after swimming contained in the summer season time warm climate yet a wine for dinner,or a blended drink for the period of the trip journeys at a party.I dont drink conventional and purely as quickly as I do do no longer could paintings(or force) do I drink