Monitoring Carbonation Level

I have a batch of sweet sparkling cyser that I just primed and bottled.

The plan is to open one every week or so until it is sufficiently carbonated and then pasteurize the remaining bottles before leaving them to age.

To avoid opening too many bottles, I put the odd amount in a zip-lock bag. The idea here is that I monitor the bag. It's starting to expand, so I know that carbonation is happening, but slowly.

The missing piece, however, is that I do not know how to equate the expansion to "carb level". Any thoughts on how much space CO2 would take out out of liquid if there were enough to carbonate a 16oz bottle of liquid?

Next time, do what I do. Take a brown PET bottle (I use the 1L ones that came with my Mr.Beer kit), or even a pop bottle, and treat it like you would a normal beer bottle. Now, to monitor carb levels, just sqeeze that bottle. If it's hard, it's carbed.

Now, if you want to convert volume into pressure, just use the ideal gas law, PV=nRT. Since nRT remains constant, then just solve for either P or V. So P=(nRT)/V or V=(nRT)/P.
http://www.calctool.org/CALC/chem/c_thermo/ideal_gas
http://www.chemicool.com/idealgas.html

*edit* what's crazy is I don't remember dealing with the ideal gas law in college chem, but I do remember it from highschool chem. What's up with that!?

Thanks for the tip. I think the plastic bottle is the way to go!

dmomo said:

Thanks for the tip. I think the plastic bottle is the way to go!

Click to expand...

Yeah, it's so easy and convenient that I will continue do it for all of my batches that I bottle and probably even when I keg, if I don't force carb. For this reason alone, i'm glad I started out with Mr.Beer.