FIZZ KEEPER SCAM
The Fizz-Keeper is a SCAM. It doesn't work. You believe that you are holding back the C02 gas with pumped air. You cannot hold back C02 gas with air. Yep I got Caught Too!Why doesn’t the Fizz-Keeper work? Let’s look at Henry’s law—this time, reading the
fine print. Remember that the law relates the solubility of a gas in a liquid to the pressure of that same gas above the liquid. In other words, the only way to increase the solubility of CO2 in the soda is to increase the pressure of CO2 above the soda. Simply pumping air (which contains very little CO2) above the soda has no effect on how much CO2 stays in solution.This isn’t easy to understand. Common sense suggests that increasing the pressure of any gas above a liquid would help to keep any gas from escaping from solution.
But this is not the case. And we need yet another gas law—Dalton’s law of partial ressures—to clear things up. Dalton’s law states that the total pressure of gases in a container is equal to the sum of all the partial pressures in that container. If gas A and gas B are each exerting a pressure of 0.5 atm in the same sealed container, they will exert a total pressure of 1 atm, the sum of their separate partial pressures. Now suppose that gas A can be completely removed. Its removal would have no effect on the partial pressure of gas B—it’s still 0.5 atm, no matter what happens to gas A. Also, if more of gas A is introduced into the container, this will have no effect on the partial pressure of gas B. Even though the total pressure increases, the partial pressure of gas B stays the same.
Think about what happens in the headspace above a bottle of soda that was opened and then recapped. Immediately CO2 gas begins to diffuse out of solution into this space. In fact, CO2 gas continues to diffuse into the space until equilibrium has been reached. The partial pressure of CO2 that exists at equilibrium in a bottle of soda depends only on the total amount of CO2 present in the container, the volume of soda, and the volume of the headspace. It has nothing to do with how many other gases exist in this space. Pumping in more ordinary air with its generous supply of nitrogen (N2) and oxygen (O2) but scant amount of CO2 molecules just can’t do the job. The pumped-in air has nearly zero effect on how many CO2 molecules leave the soda and end up in the headspace.
Only if you had a way of pumping just CO2 into the headspace would you be able to keep CO2 in its place—in the drink. Other than buying a CO2 generator, is there any way to keep a soda from going flat? You might try decreasing the empty space over the liquid. You can try squeezing the bottle before capping to make the headspace smaller, or you can save some clean, smaller empty plastic bottles for storing the leftover soda. Less headspace means less CO2 will diffuse out of solution. And where there’s CO2, there is Fizz.
By Brian Rohrig
Brian Rohrig teaches chemistry at Eastmoor Academy in Columbus, OH. H His book, 39 Fantastic Experiments with the Fizz-Keeper, can be obtained on ebay.
Howald, R. The Fizz-Keeper: A Case Study in
Chemical Education, Equilibrium, and
Kinetics, J. Chem. Ed., Feb 1999, pp
Rohrig, B. 39 Fantastic Experiments with the
Fizz-Keeper; Creative Chemistry
Concepts: Tallmadge, OH, 1999.
The complete text of the patent for the
Fizz-Keeper (or any patented item) can be
found by accessing the U.S. Patent and Trademark
Office full text and image database at
The U.S. patent number for the Fizz-Keeper is