Will the alcohol evaporate???

[parallon]

Hello all. This may be a pretty silly question, and I haven't seen it asked yet, but my inquisitive mind wants to know whether the alcohol produced during fermentation will evaporate during this process. So, figuring your ABV using OG and FG basically tells you what you should have based on the reduced sugar, but is there a possibility that the alcohol that was created could also have evaporated?

Sorry if this is a retarded question, but hey, an inquiring mind wants to know.

Mike

 

[frazier]

You mean, I wasn't really drunk last night??

Seriously - you could ask why it doesn't evaporate, but you can't really ask if it does. People have been brewing for thousands of years, I think they would have noticed.

There's no air flow through the fermentation chamber to carry away any alcohol vapor. So, no.

 

[wildwest450]

That's how I get a 5% barelywine, leave it in the fermenter for an extra two weeks with the top off.

 

[remilard]

You mean, I wasn't really drunk last night??

Seriously - you could ask why it doesn't evaporate, but you can't really ask if it does. People have been brewing for thousands of years, I think they would have noticed.

There's no air flow through the fermentation chamber to carry away any alcohol vapor. So, no.

Obviously both water and alcohol in non-sealed fermentors evaporate, both at negligible rates.

If you have an airlock, presumably you believe c02 passes through it. Why wouldn't you believe that water and ethanol vapor do as well?

 

[Demfer]

Hello all. This may be a pretty silly question, and I haven't seen it asked yet, but my inquisitive mind wants to know whether the alcohol produced during fermentation will evaporate during this process. So, figuring your ABV using OG and FG basically tells you what you should have based on the reduced sugar, but is there a possibility that the alcohol that was created could also have evaporated?

Sorry if this is a retarded question, but hey, an inquiring mind wants to know.

Mike

The only "major" and I use that term very loosley perhaps the "most noticable" evaporation comes with distillation when aging, lets say whisky in barrels. The wood is pourous so you do have some loss commonly refered to as the "angels share".

 

[Demfer]

Obviously both water and alcohol in non-sealed fermentors evaporate, both at negligible rates.

If you have an airlock, presumably you believe c02 passes through it. Why wouldn't you believe that water and ethanol vapor do as well?

There is an air pressure differential between the air outside the fermenter as well as the C02 coming off the fermentation that is holding up the air volume within the container.

 

[GaryJohn]

You have to heat up the alcohol to have it evaporate at any noticable rate. Otherwise, no. I mean, technically it might evaporate a little, but not anything we have to worry about.

There are no stupid questions, just stupid answers!

 

[parallon]

Demfer, so, in the case of the mini-brew system, that doesn't really condone sealed units, there is still no possibility of evaporation because of the blanket of CO2? Air is required for evaporation?

 

[parallon]

Oops, sorry GaryJohn, hit Submit a little too quick.

 

[iron_city_ap]

I think you lose some, but its not enough to be signifigant or noticeable. Assuming you leave the lid and airlock on.

 

[parallon]

Ok, thanks you all. This forum is a God sent.

Mike

 

[Demfer]

Demfer, so, in the case of the mini-brew system, that doesn't really condone sealed units, there is still no possibility of evaporation because of the blanket of CO2? Air is required for evaporation?

It comes down to the fact that you need heat for evaporation phase change. The density and of a C02 blanket with the concentration of air pressure outside of the fermenter allows for a solid retention. For our purposes evaporation is minimal. Many factors influence evaporation:

Temperature: In spite of the occurrence of evaporation at all temperatures, as the temperature increases, the rate of evaporation increases. Increase in the temperature results in the increase of kinetic energy acquiring sufficient energy for escape into the vapour phase.

Intermolecular forces of the liquid: When the intermolecular forces in a liquid are weak, escape of molecules is easier from the surface resulting in an increase in the rate of evaporation. At high intermolecular forces between molecules in a liquid, only those molecules escape, which have sufficient energy to overcome the intermolecular attraction.

Surface area: The area that is exposed to evaporation directly influences the rate of evaporation. Larger the surface area, greater is the rate of evaporation of the liquid.

Heat: The vibrations within the molecules of hot liquid are very high and hence result in easier escape from the surface of the liquid.

Nature of the liquid: The liquid that contains large charged molecules result in a slow evaporation process with the requirement of additional energy for overcoming the electromagnetic interactions that allow the molecules to escape.

Gaseous molecules: The amount of molecules in the gaseous phase that is present surrounding the liquid molecules, the number of molecules that escape from the surface of the liquid is higher when the number of gas molecules present is high.

Introducing the liquid to vacuum instantly removes the gas before getting converting back to the liquid state, resulting in an enormous rate of evaporation.

The density of the liquid is inversely related to the rate of evaporation. The higher the density of the liquid, the rate of evaporation is slow.

Rate of airflow: Movement of fresh air over the substance increases the concentration of the substance in the air resulting in an increased rate of evaporation.

Concentration of the substance: The concentration of the substance that is evaporating directly influences the evaporation rate and the presence of impurities inversely influences the rate of evaporation.

 

[remilard]

Sooooo you now admit that alcohol and water evaporate out of non-sealed fermentors?

Thanks, they always come around eventually.

 

[Justibone]

Sooooo you now admit that alcohol and water evaporate out of non-sealed fermentors?

It is not significant.

 

[Demfer]

Sooooo you now admit that alcohol and water evaporate out of non-sealed fermentors?

Thanks, they always come around eventually.

Haha, everything evaporates its just the level of evap in this case is not at all something makes significant impact.

 

[devilishprune]

I would consider the fermenter to be a sealed environment after fermentation is over, even though it can still release gas to the rest of the atmosphere. I also think that the alcohol does evaporate, as well as the water (I always get condensation on the lid of my fermentors), but it just isn't at enough of a rate to increase the pressure inside the fermentor and bubble out of the airlock.

The vapors inside the fermentor's headspace are going to be in equilibrium with their counterparts in the beer itself. So after some initial evaporation from the beer, then you are going to have constant rates of evaporation and condensation back into the beer.

I suppose that the more you take the lid off, the more evaporation you're going to get, but I don't think that it's going to matter at all. Since evaporation of ethanol will take place at a greater rate than that of water, if ethanol evaporation were a problem then it would cause SG to increase. Ethanol is less dense than water, and also it would reduce the volume of the beer with the same amount of sugars in solution.

 

[damnyankee]

Hello all. This may be a pretty silly question, and I haven't seen it asked yet, but my inquisitive mind wants to know whether the alcohol produced during fermentation will evaporate during this process. So, figuring your ABV using OG and FG basically tells you what you should have based on the reduced sugar, but is there a possibility that the alcohol that was created could also have evaporated?

Sorry if this is a retarded question, but hey, an inquiring mind wants to know.

Mike

I have an education in chemistry/physics and as a few other posters stated, there are variables to your answer.

They are correct there are several factors influencing evaporation, however the two primary factors are water vapor and ethanol vapor in the room/vessel. The higher the water vapor and ethanol vapor in the vessel/room, the higher their partial pressures are exerted onto the top of the solution, and the less ethanol will leave solution to evaporate in the vessel or in the room.

In regards to your fermentation vessel, the other posters are correct: once the ethanol vapor reaches a certain partial pressure and exerts force onto the solution, ethanol will cease coming out of solution. How much (what % loss) will require a complicated calculation based on temp, vapor pressures, vessel/room size, ethanol in solution, etc etc etc.

DY

 

[parallon]

Well, I do thank you all. I value all your answers.

May the beer gods bless you all!

Mike

 

[camlinhall]

You have to heat up the alcohol to have it evaporate at any noticable rate. Otherwise, no. I mean, technically it might evaporate a little, but not anything we have to worry about.

There are no stupid questions, just stupid answers!

I've heard a few stupid questions in my time.
Although this isn't one of them by any means!

 

[unionrdr]

When you take a specific gravity measurement,you're measuring the lighter alcohol against what heavier sugars are left in the beer. The sugary wort is denser,making the hydrometer float upward more. As the wort ferments,it makes more alcohol,being lighter,makes the hydrometer sink more. so I don't think it's evaporating,otherwise,hydrometer readings wouldn't be possible to the extent that it is.