alc concentration

stoker · Post by **stoker** » Sat May 06, 2006 8:39 am

ABV, % and ° are all concentrations, but are they calculated by mass or volume? all of them?

possum · Post by **possum** » Sat May 06, 2006 8:57 am

usually, ABV is expressed as %ABV and it means :percent alcohol by VOLUME. The measurement is usually done by density, unless there is a lot of sugar disolved in the spirit, in that case, the refraction of light is sometimes used to determine the %ABV.

You could measure alcohol content in moles/liter....molality I belive it is called, but only a chemist would be likely to use such a measure.

proof....the degree symbol depends on the nationality of the person expressing it.

Brittish "proof" expresses 50%ABV at 57proof
American "proof" express 50% ABV at 100proof

check here for more info http://en.wikipedia.org/wiki/Alcoholic_proof" onclick="window.open(this.href);return false;" rel="nofollow

stoker · Post by **stoker** » Sat May 06, 2006 2:11 pm

ty
so, the 3 methodes I mentioned are all calculated by volume?

molality

molarity

possum · Post by **possum** » Tue May 09, 2006 4:00 pm

molality and molarity are two related but different things.
molarity is moles/liter,

and molality is (I think) moles/(Kg of innert stuff) .

% could be measured in many ways, % by weight, volume or whatever.

The standard in Europe (and UK) and North America is %ABV. Most countries require %ABV listed on the bottle even if another system of measure is also used.

Watershed · Post by **Watershed** » Wed May 10, 2006 6:49 am

Molarity is basicaly amount of substance in grams divided by its atomic weight and divided by the volume of solution in litres.

We rarely use it for liquid:liquid mixtures as it's inconvenient unless you need to know it for reaction purposes, our ethanol is always done as % by putting the ethanol in first then adding water - it makes a difference as there's a volume change involved.

40% ethanol is 6.9M , 100% ethanol is 17.2M so half a litre of it contains 8.6 moles of ethanol and if you multiply that by avagadros constant you know how many molecules are in your drink.

I've got to get put more

stoker · Post by **stoker** » Wed May 10, 2006 6:59 am

thank you

sorry for the undeserved correction,
molality sounds weird

possum · Post by **possum** » Wed May 10, 2006 7:47 am

no sweat, I mixed up the definitions in my first post. I don't do too much chem recently.

The Chemist · Post by **The Chemist** » Thu May 11, 2006 5:20 am

stoker wrote:thank you

sorry for the undeserved correction,
molality sounds weird

Molality IS weird!!!

Another unit used often is distillation theory is "mole percent", i.e. ((mol EtOH)/(mol EtOH + mol H2O))*100=mole percent ethanol

grunther777 · Post by **grunther777** » Fri May 26, 2006 11:33 pm

ok I have a math related question. For some reason I cant reasure myself with the answer. If I have 14 L of 100% alcohol in a 100 L batch how many litres of 85% alcohol is in the batch. I'm thinking 16.5 L . Its late and I wond be able to sleeep unless I figure it out.

stoker · Post by **stoker** » Sat May 27, 2006 12:48 am

it's correct
16.5*85/100=14

Harry · Post by **Harry** » Sat May 27, 2006 3:07 am

Watershed wrote: I've got to get put more

Put??!!?? You mean *laid*.