Bubbles in a soft drink each nucleate independently, responding to a decrease in pressure.

Nucleation is the onset of a phase transition in a small region. The phase transition can be the formation of a bubble or of a crystal from a liquid. Creation of liquid droplets in saturated vapor or the creation of gaseous bubble in a saturated liquid is also characterized by nucleation (see Cloud condensation nuclei). Macro photograph of coca-cola bubbles. ... Macro photograph of coca-cola bubbles. ... A soft drink is a drink that contains no alcohol. ... This article is about pressure in the physical sciences. ... In physics, a phase transition, (or phase change) is the transformation of a thermodynamic system from one phase to another. ... Look up bubble in Wiktionary, the free dictionary. ... For other uses, see Crystal (disambiguation). ... For other uses, see Liquid (disambiguation). ... See also drop (telecommunication). ... Vapor (US English) or vapour (British English) is the gaseous state of matter. ... Bubbles is a Swedish girls bubblegum pop group. ... For other uses, see Liquid (disambiguation). ... Aerosol pollution over Northern India and Bangladesh - NASA Cloud condensation nuclei or CCNs (also known as cloud seeds) are small particles (typically 0. ...

Nucleation normally occurs at nucleation sites on surfaces containing the liquid or vapour. Suspended particles or minute bubbles also provide nucleation sites. This is called heterogeneous nucleation. Nucleation without preferential nucleation sites is homogeneous nucleation. Homogeneous nucleation occurs spontaneously and randomly, but it requires superheating or supercooling of the medium. Nucleation is involved in such processes as cloud seeding and in instruments such as the bubble chamber and the cloud chamber. In physics, superheating (sometimes referred to as boiling retardation, boiling delay, or defervescence) is the phenomenon in which a liquid is heated to a temperature higher than its standard boiling point, without actually boiling. ... Supercooling is the process of chilling a liquid below its freezing point, without it becoming solid. ... Cessna 210 with cloud seeding equipment Cloud seeding, a form of weather modification, is the attempt to change the amount or type of precipitation that falls from clouds, by dispersing substances into the air that serve as cloud condensation or ice nuclei. ... A bubble chamber A bubble chamber is a vessel filled with a superheated transparent liquid used to detect electrically charged particles moving through it. ... Discovery of the positron in 1932 by Carl D. Anderson in a cloud chamber The cloud chamber, also known as the Wilson chamber, is used for detecting particles of ionizing radiation. ...

Examples of nucleation

Nucleation of carbon dioxide bubbles around a finger

• Pure water freezes at −42° C rather than at its freezing temperature of 0° C if no crystal nuclei, such as dust particles, are present to form an ice nucleus.
• Presence of cloud condensation nuclei is important in meteorology because they are often in short supply in the upper atmosphere (see cloud seeding).
• All natural and artificial crystallization process (of formation of solid crystals from a homogeneous solution) starts with a nucleation event.
• Bubbles of carbon dioxide nucleate shortly after the pressure is released from a container of carbonated liquid. Nucleation often occurs more easily at a pre-existing interface (heterogeneous nucleation), as happens on boiling chips and string used to make rock candy. So-called Diet Coke and Mentos eruptions are a dramatic example.
• Nucleation in boiling can occur in the bulk liquid if the pressure is reduced so that the liquid becomes superheated with respect to the pressure-dependent boiling point. More often nucleation occurs on the heating surface, at nucleation sites. Typically, nucleation sites are tiny crevices where free gas-liquid surface is maintained or spots on the heating surface with lower wetting properties. Substantial superheating of a liquid can be achieved after the liquid is de-gassed and if the heating surfaces are clean, smooth and made of materials well wetted by the liquid.
• Nucleation is a key concept in polymer ^[1], alloy, and ceramic systems.
• In chemistry and biophysics, nucleation can also refer to the phaseless formation of multimers which are intermediates in polymerization processes. This sort of process is believed to be the best model for processes such as crystallization and amyloidogenesis.
• In molecular biology, nucleation is used to term the critical stage in the assembly of a polymeric structure, such as a microtubule, at which a small cluster of monomers aggregates in the correct arrangement to initiate rapid polymerization. For instance, two actin molecules bind weakly, but addition of a third stabilizes the complex. This trimer then adds additional molecules and forms a nucleation site. The nucleation site serves the slow, or lag phase of the polymerization process.

Image File history File links Size of this preview: 800 × 597 pixelsFull resolution (1030 × 768 pixel, file size: 299 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Size of this preview: 800 × 597 pixelsFull resolution (1030 × 768 pixel, file size: 299 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... In physics and chemistry, freezing is the process whereby a liquid turns to a solid. ... An ice nucleus is a particle which acts as the nucleus for the formation of an ice crystal in the atmosphere. ... Aerosol pollution over Northern India and Bangladesh - NASA Cloud condensation nuclei or CCNs (also known as cloud seeds) are small particles (typically 0. ... // Meteorology (from Greek: μετέωρον, meteoron, high in the sky; and λόγος, logos, knowledge) is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and forecasting. ... For other uses, see Atmosphere (disambiguation). ... Cessna 210 with cloud seeding equipment Cloud seeding, a form of weather modification, is the attempt to change the amount or type of precipitation that falls from clouds, by dispersing substances into the air that serve as cloud condensation or ice nuclei. ... Frost crystallization on a shrub. ... Crystal (disambiguation) Insulin crystals A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... For the chemical reaction forming calcium carbonate, see carbonatation. ... An interface is a surface forming a common boundary between two substances forming a colloid, such as oil & water or water & air. ... Boiling chips are small, irregularly shaped stones used to prevent bumping of liquids during heating, boiling, or distillation. ... Rock candy is a type of confectionery composed of relatively large sugar crystals. ... A handful of Mentos in a two liter Diet Coke bottle produces an eruption. ... Boiling, a type of phase transition, is the rapid vaporization of a liquid, which typically occurs when a liquid is heated to its boiling point, the temperature at which the vapor pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmospheric pressure. ... For other uses, see Liquid (disambiguation). ... In physics, superheating (sometimes referred to as boiling retardation, boiling delay, or defervescence) is the phenomenon in which a liquid is heated to a temperature higher than its standard boiling point, without actually boiling. ... Wetting of different fluids. ... A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... An alloy is a homogeneous mixture of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ... Fixed Partial Denture, or Bridge The word ceramic is derived from the Greek word κεραμικός (keramikos). ... For other uses, see Chemistry (disambiguation). ... Biophysics (also biological physics) is an interdisciplinary science that applies the theories and methods of physics, to questions of biology. ... Frost crystallization on a shrub. ... For other uses, see Amyloid (disambiguation). ... Molecular biology is the study of biology at a molecular level. ... A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... In chemistry, a monomer (from Greek mono one and meros part) is a small molecule that may become chemically bonded to other monomers to form a polymer. ... G-Actin (PDB code: 1j6z). ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ...

Mechanics of nucleation

Homogeneous nucleation

Nucleation generally occurs with much more difficulty in the interior of a uniform substance, by a process called homogeneous nucleation. Liquids cooled below the maximum heterogeneous nucleation temperature (melting temperature), but which are above the homogeneous nucleation temperature (pure substance freezing temperature) are said to be supercooled. This is useful for making amorphous solids and other metastable structures, but can delay the progress of industrial chemical processes or produce undesirable effects in the context of casting. In physics, melting is the process of heating a solid substance to a point (called the melting point) where it turns into a liquid. ... In physics and chemistry, freezing is the process whereby a liquid turns to a solid. ... Supercooling is the process of chilling a liquid below its freezing point, without it becoming solid. ... Wax and paraffin are amorphous. ... A metastable system with a weakly stable state (1), an unstable transition state (2) and a strongly stable state (3) Metastability is the ability of a non-equilibrium state to persist for some period of time. ... For other uses, see Chemistry (disambiguation). ... This article is about the manufacturing process. ...

The creation of a nucleus implies the formation of an interface at the boundaries of the new phase. Some energy is expended to form this interface, based on the surface energy of each phase. If a hypothetical nucleus is too small, the energy that would be released by forming its volume is not enough to create its surface, and nucleation does not proceed. The critical nucleus size can be denoted as by its radius, and it is when r=r* (or r critical) that the nucleation proceeds. As the phase transformation becomes more and more favorable, the formation of a given volume of nucleus frees enough energy to form an increasingly large surface, allowing progressively smaller nuclei to become viable. Eventually, thermal activation will provide enough energy to form stable nuclei. These can then grow until thermodynamic equilibrium is restored. Surface energy quantifies the disruption of chemical bonds that occurs when a surface is created. ... The sparks generated by striking steel against a flint provide the activation energy to initiate combustion in this Bunsen burner. ... In thermodynamics, a thermodynamic system is said to be in thermodynamic equilibrium when it is in thermal equilibrium, mechanical equilibrium, and chemical equilibrium. ...

The spontaneous nucleation rate in, say, water changes very rapidly with temperature, so the spontaneous nucleation temperature can be quite well defined. 'Film boiling' on very hot surfaces and the Leidenfrost effect are both believed to be stabilized by spontaneous nucleation phenomena. The Leidenfrost effect is the phenomenon in which a liquid in near contact with a mass hotter than the liquids Leidenfrost point, which is higher than its boiling point, produces an insulating vapor layer which keeps it from boiling rapidly. ...

Heterogeneous nucleation

In the case of heterogeneous nucleation, some energy is released by the partial destruction of the previous interface. For example, if a carbon dioxide bubble forms between water and the inside surface of a bottle, the energy inherent in the water-bottle interface is released wherever a layer of gas intervenes, and this energy goes toward the formation of bubble-water and bubble-bottle interfaces. The same effect can cause precipitate particles to form at the grain boundaries of a solid. This can interfere with precipitation strengthening, which relies on homogeneous nucleation to produce a uniform distribution of precipitate particles. A crystallite is a domain of solid-state matter that has the same structure as a single crystal. ... Precipitation hardening, also called age hardening or dispersion hardening, is a heat treatment technique used to strengthen malleable materials, especially non-ferrous alloys including most structural alloys of aluminium and titanium. ...

Theory of the spinodal region nucleation

Nucleation processes can also be explained in terms of spinodal decomposition where phase separation is delayed until the system enters the unstable region where a small perturbation in composition leads to a decrease in energy and thus spontaneous growth of the perturbation. This region of a phase diagram is known as the spinodal region and the phase separation process is known as spinodal decomposition and may be governed by the Cahn-Hilliard Equation. A homogeneous quench occurs when a control parameter, such as temperature, is abruptly and globally changed from a stable to an unstable region of the phase diagram. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... The Cahn-Hilliard equation is an equation of mathematical physics which describes the process of phase separation, by which the two components of a binary fluid spontaneously separate and form domains pure in each component. ...

See also

• Cloud condensation nuclei, the basis for the development of a cloud droplet
• Critical radius
• Seed crystal
• Freezing
• Ice nucleus, the center of an ice crystal
• Manganese nodule
• Supercooling
• Diet Coke and Mentos eruption

Aerosol pollution over Northern India and Bangladesh - NASA Cloud condensation nuclei or CCNs (also known as cloud seeds) are small particles (typically 0. ... This article or section does not cite its references or sources. ... A seed crystal is a small piece of single crystal material from which a large crystal of, usually, the same material is to be grown. ... In physics and chemistry, freezing is the process whereby a liquid turns to a solid. ... An ice nucleus is a particle which acts as the nucleus for the formation of an ice crystal in the atmosphere. ... Polymetallic nodules, also called manganese nodules, are rock concretions on the sea bottom formed of concentric layers of iron and manganese hydroxides around a core. ... Supercooling is the process of chilling a liquid below its freezing point, without it becoming solid. ... A handful of Mentos in a two liter Diet Coke bottle produces an eruption. ...

References

External links

• The Extreme Diet Coke & Mentos Experiments - fun with nucleation