farmbrewernw
Well-Known Member
Can someone explain to me what volumes of CO2 means? I know how to carbonate a beer right I just want to know what the volume means, is it part's per million or a percentage of the liquid, or ????
Listen to this brew strong episode. It's all about carbonation, and they explain it very well.
1 volume is 1 liter of CO2 at 1 atmosphere in 1 liter of fluid (beer). You can substitute gal for liter.
GT
1 volume is 1 liter of CO2 at 1 atmosphere in 1 liter of fluid (beer). You can substitute gal for liter.
GT
When referring to volumes of CO2 per style like 2.5, is this referring to volumes of CO2 that would dissolve at serving temperature or volumes at 20C? I've been assuming serving temp but I've never been quite sure.
Also I've seen suggested volumes for different styles of beer go pretty high, over 5 volumes, does anybody know what volume it would take to get a bottle bomb? How much pressure can a typical brown long neck hold before breaking?
shortyjacobs said:Close.
1 volume is 1 liter of CO2 at 20°C at 1 atmosphere in 1 liter of beer.
(OP, this also means 1 volume is 5 gallons of CO2 at 20°C at 1 atm in 5 gallons of beer)
Heavyfoot said:Does anyone know how many volumes of co2 would exist in water under no pressure? Would it be 1 volume at 20 C?
Anyone?
zachattack said:Henry's law states that the concentration of a gas dissolved in a liquid is directly proportional to the pressure of gas above the liquid.
If you have water exposed to an atmosphere, once everything equilibrates, the CO2 concentration in the water is Henry's constant (which is different for each gas/liquid combo and highly dependent on temperature) multiplied by the pressure of CO2 in the atmosphere.
If you're talking about Earth's atmosphere, that would be something like 0.04% CO2. So the amount that would dissolve in water is 0.0004 atm * .035 mol CO2/kg*atm (henry's law constant at 20 degrees C, I got this from here) = .000014 mol CO2/kg water. At 20 deg C ideal volume is 24.5 L/mol, so that's 0.000343 liters CO2 per liter of water (or volumes of CO2)
So not a lot.
If you have an atmosphere of pure CO2 (the case in a well-sealed carboy under ambient pressure after primary fermentation), and use this same formula, you'd have 0.8575 volumes. This is the CO2 present in the beer before you even add priming sugar, and that's why the fermentation temperature is important when calculating how much priming sugar to add.
I love this stuff, but then again I'm a chemical engineer :rockin:
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