effervescing

Effervescing is the rapid release of gas from a liquid, typically visible as bubbles that rise to the surface and may create foam. It occurs when a gas becomes undersaturated in the liquid, or when a chemical reaction generates gas, causing it to escape from solution.

In chemistry, effervescence describes visible bubbling from gas evolution. For example, in acid-base or carbonate reactions, carbon dioxide is produced and escapes as bubbles: CaCO3 + 2HCl → CaCl2 + CO2 + H2O. The phenomenon can also occur when a liquid is supersaturated with dissolved gas and a disturbance or seed particles initiate bubble formation.

In everyday contexts, effervescence is most familiar in carbonated beverages. Carbon dioxide is dissolved in the liquid under pressure; when the container is opened or the liquid is warmed, the pressure drop or increased temperature reduces gas solubility, prompting CO2 to come out of solution and form bubbles. The rate and vigor of effervescence depend on factors such as temperature, pressure, agitation, and the presence of nucleation sites such as imperfections or particles.

Effervescent products also include tablets that dissolve in water to rapidly release carbon dioxide, creating fizzy solutions. In addition to beverages and medical tablets, effervescence occurs in fermentation and various chemical reactions where gas is produced.

Effervescence is distinct from boiling: boiling is bulk vaporization driven by heat, whereas effervescence is driven by changes in gas solubility or gas production, with bubbling arising from gas entering or leaving the liquid phase.