Applied Fizzics Research Notes

This Research Note calculates the expansion energy available from compressed gas in a pressurized Champagne bottle. Isothermal and adiabatic models are compared for full and nearly empty bottles at the same pressure, showing that while the calculated energy depends on the thermodynamic model, the energy ratio scales directly with compressed-gas volume.

Can we predict the pressure inside a bottle of Champagne from the sugar used to create its bubbles? Starting with 18 grams of sugar, we follow the CO₂ from fermentation to the finished bottle—and discover why Champagne carbonation is reversible.

A sealed bottle of carbonated liquid contains carbon dioxide in two obvious places: dissolved in the liquid and as gas in the headspace above it. How much resides in each?

The result is surprisingly. For pure water, there are approximately 1.45 times as many CO₂ molecules in solution per unit volume as there are in the headspace at refrigerator temperatures of ~5C. For Champagne, the ratio is closer to 1.25.

This simple result also raises a second question: Is the large liquid fraction caused by conversion of dissolved CO₂ to carbonic acid? As we shall see, that appealing explanation does not account for the effect.

References in the literature can be found suggesting that 80% of the CO2 loss in a flute of Champagne is due to molecular diffusion at the liquid-air interface, and only 20% is lost due to visible bubbles. In this Applied Fizzics Research Note, we examine this proposition in detail.