Effervescence is the escape of gas from an aqueous solution and the foaming or fizzing that results from a release of the gas. The word effervescence is derived from the Latin verb fervere (to boil), preceded by the adverb ex. It has the same linguistic root as the word fermentation, a complex biochemical reaction leading to, among other things, the production of carbon dioxide and to the subsequent liberation of CO2 gas from a solution when it becomes supersaturated with respect to this gas. The making of beer, wine, or champagne by fermentation is thus accompanied by effervescence of CO2 from the barrel where the process occurs.
Effervescence can also be observed when opening a bottle of champagne, beer or carbonated beverages such as soft drinks. The visible bubbles are produced by the escape from solution of the dissolved gas (which itself is not visible while dissolved in the liquid).
Although CO2 is most common for beverages, nitrogen gas is sometimes deliberately added to certain draught beers. The smaller bubble size creates a smoother beer head. Due to the poor solubility of nitrogen in beer, kegs or widgets are used for this.
In the laboratory, a common example of effervescence is seen if hydrochloric acid is added to a block of limestone. If a few pieces of marble or an antacid tablet are put in hydrochloric acid in a test tube fitted with a bung, effervescence of carbon dioxide can be witnessed.
- CaCO3 + 2 HCl → CaCl2 + H2O + CO2
- H2CO3 → H2O + CO2
In simple terms, it is the result of the chemical reaction occurring in the liquid which produces a gaseous product.
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- Baxter, E. Denise; Hughes, Paul S. (2001). Beer: Quality, Safety and Nutritional Aspects. Royal Society of Chemistry. p. 22. ISBN 9780854045884.
- G. Liger-Belair et al., "Study of Effervescence in a Glass of Champagne: Frequencies of Bubble Formation, Growth Rates, and Velocities of Rising Bubbles", Am. J. Enol. Vitic. 50:3 (1999) 317–323