Fizz-Keeper facts for kids

The Fizz-Keeper is a device that is sold as a means for preserving the carbonation in soft drinks. It comprises a small hand pump that screws onto the top of a plastic soft drink bottle, which is used to pump air into the bottle. Pressurizing the bottle in this way, it is claimed by most of those who sell the device, prevents the drink from going flat.

Scientists who have analyzed the process in detail have shown, however, that pressurizing the bottle does not prevent the drink from going flat, although it may slow down the process somewhat.

Description

The first Fizz-Keeper-like device was patented in 1926 by G. Staunton. T.R. Robinson and M.B. Beyer patented the Fizz-Keeper itself in 1988, without claiming in the patent that the device maintained a soft drink's "fizz". Several styles of device exist, from the plain piston pump to devices incorporating a bulb and a latch and hinge device to allow liquid to be poured out of a spout without removing the Fizz-Keeper from the bottle.

The kinetics of the loss of "fizz" (CO₂) after pouring out part of the liquid and resealing the bottle is somewhat complicated, but the computation of the final equilibrium concentration of CO₂ in the liquid and the gas phase can be done (with or without pumping air into the bottle) using Dalton's law (a consequence of ideal gas theory). This shows that the equilibrium CO₂ concentrations are independent of the air pressure -- the device does not prevent loss of CO₂ from the liquid. This conclusion does not require knowledge of Dalton's law -- it can be seen directly from the fundamental assumption of ideal gas theory, that molecules in the gas phase do not interact with one another. This principle implies that the behavior of the CO₂ is completely independent of the behavior of the air (nitrogen and oxygen), or of how much air is present -- pumping air into the bottle has no effect whatsoever on the CO₂. Studies of the kinetics, however, do report that the increased overall pressure slows down the rate at which dissolved CO₂ comes out of solution, so the application of the Fizz-Keeper extends this process, but by hours not by days. Rohrig reports that this can be and has been easily confirmed by experiment.

The Fizz-Keeper also has documented uses as a home science tool and teaching aid, for experimentation in physics. Rohrig has published a book of science experiments that can be performed with the Fizz-Keeper. More experiments have been published by Moloney, Spangler, Graham, and Williams et al. (All are listed in further reading.)

See also

In Spanish: Fizz keeper para niños