Liquid is a form of matter with a definite volume but no fixed shape. A liquid is made up of tiny vibrating particles of matter, such as atoms and molecules, held together by forces called chemical bonds. Water is, by far, the most common liquid on Earth. Liquid is one of the three classical states of matter (the others being gas and solid). Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly constant density. A distinctive property of the liquid state is surface tension, leading to wetting phenomena.

The density of a liquid is usually close to that of a solid, and much higher than in a gas. Therefore, liquid and solid are both termed condensed matter. On the other hand, as liquids and gases share the ability to flow, they are both called fluids.

The formation of a spherical droplet of liquid water minimizes the surface area, which is the natural result of surface tension in liquids.

Introduction[link]

Liquid is one of the three primary states of matter, with the others being solid and gas. A liquid is a fluid. Unlike a solid, the molecules in a liquid have a much greater freedom to move. The forces that bind the molecules together in a solid are only temporary in a liquid, allowing a liquid to flow while a solid remains rigid.

A liquid, like a gas, displays the properties of a fluid. A liquid can flow, assume the shape of a container, and, if placed in a sealed container, will distribute applied pressure evenly to every surface in the container. Unlike a gas, a liquid may not always mix readily with another liquid, will not always fill every space in the container, forming its own surface, and will not compress significantly, except under extremely high pressures. These properties make a liquid suitable for applications such as hydraulics.

Liquid particles are bound firmly but not rigidly. They are able to move around one another freely, resulting in a limited degree of particle mobility. As the temperature increases, the increased vibrations of the molecules causes distances between the molecules to increase. When a liquid reaches its boiling point, the cohesive forces that bind the molecules closely together break, and the liquid changes to its gaseous state (unless superheating occurs). If the temperature is decreased, the distances between the molecules become smaller. When the liquid reaches its freezing point the molecules will usually lock into a very specific order, called crystallizing, and the bonds between them become more rigid, changing the liquid into its solid state (unless supercooling occurs).

Examples[link]

Only two elements are liquid at standard conditions for temperature and pressure: mercury and bromine. Five more elements have melting points slightly above room temperature: francium, caesium, gallium and rubidium.^[1] Metal alloys that are liquid at room temperature include NaK, a sodium-potassium metal alloy, galinstan, a fusible alloy liquid, and some amalgams (alloys involving mercury).

Pure substances that are liquid under normal conditions include water, ethanol and many other organic solvents. Liquid water is of vital importance in chemistry and biology; it is believed to be a necessity for the existence of life.

Important everyday liquids include aqueous solutions like household bleach, other mixtures of different substances such as mineral oil and gasoline, emulsions like vinaigrette or mayonnaise, suspensions like blood, and colloids like paint and milk.

Many gases can be liquefied by cooling, producing liquids such as liquid oxygen, liquid nitrogen, liquid hydrogen and liquid helium. Not all gases can be liquified at atmospheric pressure, for example carbon dioxide can only be liquified at pressures above 5.1 atm.

Some materials cannot be classified within the classical three states of matter; they possess solid-like and liquid-like properties. Examples include liquid crystals, used in LCD displays, and biological membranes.

Applications[link]

Liquids have a variety of uses, as lubricants, solvents, and coolants. In hydraulic systems, liquid is used to transmit power.

In tribology, liquids are studied for their properties as lubricants. Lubricants such as oil are chosen for viscosity and flow characteristics that are suitable throughout the operating temperature range of the component. Oils are often used in engines, gear boxes, metalworking, and hydraulic systems for their good lubrication properties.^[2]

Many liquids are used as solvents, to dissolve other liquids or solids. Solutions are found in a wide variety of applications, including paints, sealants, and adhesives. Naptha and acetone are used frequently in industry to clean oil, grease, and tar from parts and machinery. Body fluids are water based solutions.

Surfactants are commonly found in soaps and detergents. Solvents like alcohol are often used as antimicrobials. They are found in cosmetics, inks, and liquid dye lasers. They are used in the food industry, in processes such as the extraction of vegetable oil.^[3]

Liquids tend to have better thermal conductivity than gases, and the ability to flow makes a liquid suitable for removing excess heat from mechanical components. The heat can be removed by channeling the liquid through a heat exchanger, such as a radiator, or the heat can be removed with the liquid during evaporation.^[4] Water or glycol coolants are used to keep engines from overheating.^[5] The coolants used in nuclear reactors include water or liquid metals, such as sodium or bismuth.^[6] Liquid propellant films are used to cool the thrust chambers of rockets.^[7] In machining, water and oils are used to remove the excess heat generated, which can quickly ruin both the work piece and the tooling. During perspiration, sweat removes heat from the human body by evaporating. In the heating, ventilation, and air-conditioning industry (HVAC), liquids such as water are used to transfer heat from one area to another.^[8]

Liquid is the primary component of hydraulic systems, which take advantage of Pascal's law to provide fluid power. Devices such as pumps and waterwheels have been used to change liquid motion into mechanical work since ancient times. Oils are forced through hydraulic pumps, which transmit this force to hydraulic cylinders. Hydraulics can be found in many applications, such as automotive brakes and transmissions, heavy equipment, and airplane control systems. Various hydraulic presses are used extensively in repair and manufacturing, for lifting, pressing, clamping and forming.^[9]

Liquids are sometimes used in measuring devices. A thermometer often uses the thermal expansion of liquids, such as mercury, combined with their ability to flow to indicate temperature. A manometer uses the weight of the liquid to indicate air pressure.^[10]

Mechanical properties[link]

Volume[link]

Quantities of liquids are commonly measured in units of volume. These include the SI unit cubic metre (m³) and its divisions, in particular the cubic decimetre, more commonly called the litre (1 dm³ = 1 L = 0.001 m³), and the cubic centimetre, also called millilitre (1 cm³ = 1 mL = 0.001 L = 10⁻⁶ m³).

The volume of a quantity of liquid is fixed by its temperature and pressure. Liquids generally expand when heated, and contract when cooled. Water between 0 °C and 4 °C is a notable exception. Liquids have little compressibility: water, for example, requires a pressure of the order of 200 bar to increase its density by 1/1000. In the study of fluid dynamics, liquids are often treated as incompressible, especially when studying incompressible flow.

Pressure and buoyancy[link]

In a gravitational field, liquids exert pressure on the sides of a container as well as on anything within the liquid itself. This pressure is transmitted in all directions and increases with depth. If a liquid is at rest in a uniform gravitational field, the pressure, p, at any depth, z, is given by

Failed to parse (Missing texvc executable; please see math/README to configure.): p=\rho g z\,

where:

Failed to parse (Missing texvc executable; please see math/README to configure.): \rho\,

is the density of the liquid (assumed constant)

Failed to parse (Missing texvc executable; please see math/README to configure.): g\,

is the gravitational acceleration.

Note that this formula assumes that the pressure at the free surface is zero, and that surface tension effects may be neglected.

Objects immersed in liquids are subject to the phenomenon of buoyancy. (Buoyancy is also observed in other fluids, but is especially strong in liquids due to their high density.)

Surfaces[link]

Surface waves in water

Unless the volume of a liquid exactly matches the volume of its container, one or more surfaces are observed. The surface of a liquid behaves like an elastic membrane in which surface tension appears, allowing the formation of drops and bubbles. Surface waves, capillary action, wetting, and ripples are other consequences of surface tension.

Flow[link]

Viscosity measures the resistance of a liquid which is being deformed by either shear stress or extensional stress.

When a liquid is supercooled towards the glass transition, the viscosity increases dramatically. The liquid then becomes a viscoelastic medium that shows both the elasticity of a solid and the fluidity of a liquid, depending on the time scale of observation or on the frequency of perturbation.

Sound propagation[link]

In a fluid the only non-zero stiffness is to volumetric deformation (a fluid does not sustain shear forces). Hence the speed of sound in a fluid is given by Failed to parse (Missing texvc executable; please see math/README to configure.): c = \sqrt {K/\rho}

where K is the bulk modulus of the fluid, and ρ the density. To give a typical value, in fresh water c=1497 m/s at 25 °C.

Thermodynamics[link]

Phase transitions[link]

A typical phase diagram. The dotted line gives the anomalous behaviour of water. The green lines show how the freezing point can vary with pressure, and the blue line shows how the boiling point can vary with pressure. The red line shows the boundary where sublimation or deposition can occur.

At a temperature below the boiling point, any matter in liquid form will evaporate until the condensation of gas above reach an equilibrium. At this point the gas will condense at the same rate as the liquid evaporates. Thus, a liquid cannot exist permanently if the evaporated liquid is continually removed. A liquid at its boiling point will evaporate more quickly than the gas can condense at the current pressure. A liquid at or above its boiling point will normally boil, though superheating can prevent this in certain circumstances.

At a temperature below the freezing point, a liquid will tend to crystallize, changing to its solid form. Unlike the transition to gas, there is no equilibrium at this transition under constant pressure, so unless supercooling occurs, the liquid will eventually completely crystallize. Note that this is only true under constant pressure, so e.g. water and ice in a closed, strong container might reach an equilibrium where both phases coexist. For the opposite transition from solid to liquid, see melting.

Solutions[link]

Liquids can display immiscibility. The most familiar mixture of two immiscible liquids in everyday life is the vegetable oil and water in Italian salad dressing. A familiar set of miscible liquids is water and alcohol. Liquid components in a mixture can often be separated from one another via fractional distillation.

Microscopic properties[link]

Static structure factor[link]

Structure of a classical monatomic liquid. Atoms have many nearest neighbors in contact, yet no long-range order is present.

‎

In a liquid, atoms do not form a crystalline lattice, nor do they show any other form of long-range order. This is evidenced by the absence of Bragg peaks in X-ray and neutron diffraction. Under normal conditions, the diffraction pattern has circular symmetry, expressing the isotropy of the liquid. In radial direction, the diffraction intensity smoothly oscillates. This is usually described by the static structure factor S(q), with wavenumber q=(4π/λ)sinθ given by the wavelength λ of the probe (photon or neutron) and the Bragg angle θ. The oscillations of S(q) express the near order of the liquid, i.e. the correlations between an atom and a few shells of nearest, second nearest, ... neighbors.

A more intuitive description of these correlations is given by the radial distribution function g(r), which is basically the Fourier transform of S(q). It represents a spatial average of a temporal snapshot of pair correlations in the liquid.

Radial distribution function of the Lennard-Jones model fluid.

Sound dispersion and structural relaxation[link]

The above expression for the sound velocity Failed to parse (Missing texvc executable; please see math/README to configure.): c = \sqrt {K/\rho}

contains the bulk modulus K. If K is frequency independent then the liquid behaves as a linear medium, so that sound propagates without dissipation and without mode coupling. In reality, any liquid shows some dispersion: with increasing frequency, K crosses over from the low-frequency, liquid-like limit Failed to parse (Missing texvc executable; please see math/README to configure.): K_0
to the high-frequency, solid-like limit Failed to parse (Missing texvc executable; please see math/README to configure.): K_\infty

. In normal liquids, most of this cross over takes place at frequencies between GHz and THz, sometimes called hypersound.

At sub-GHz frequencies, a normal liquid cannot sustain shear waves: the zero-frequency limit of the shear modulus is Failed to parse (Missing texvc executable; please see math/README to configure.): G_0=0 . This is sometimes seen as the defining property of a liquid.^[11] However, just as the bulk modulus K, the shear modulus G is frequency dependent, and at hypersound frequencies it shows a similar cross over from the liquid-like limit Failed to parse (Missing texvc executable; please see math/README to configure.): G_0

to a solid-like, non-zero limit Failed to parse (Missing texvc executable; please see math/README to configure.): G_\infty

.

According to the Kramers-Kronig relation, the dispersion in the sound velocity (given by the real part of K or G) goes along with a maximum in the sound attenuation (dissipation, given by the imaginary part of K or G). According to linear response theory, the Fourier transform of K or G describes how the system returns to equilibrium after an external perturbation; for this reason, the dispersion step in the GHz..THz region is also called structural relaxation. According the fluctuation-dissipation theorem, relaxation towards equilibrium is intimately connected to fluctuations in equilibrium. The density fluctuations associated with sound waves can be experimentally observed by Brillouin scattering.

On supercooling a liquid towards the glass transition, the crossover from liquid-like to solid-like response moves from GHz to MHz, kHz, Hz, ...; equivalently, the characteristic time of structural relaxation increases from ns to μs, ms, s, ... This is the microscopic explanation for the above mentioned viscoelastic behaviour of glass-forming liquids.

Effects of association[link]

The mechanisms of atomic/molecular diffusion (or particle displacement) in solids are closely related to the mechanisms of viscous flow and solidification in liquid materials. Descriptions of viscosity in terms of molecular "free space" within the liquid^[12] were modified as needed in order to account for liquids whose molecules are known to be "associated" in the liquid state at ordinary temperatures. When various molecules combine together to form an associated molecule, they enclose within a semi-rigid system a certain amount of space which before was available as free space for mobile molecules. Thus, increase in viscosity upon cooling due to the tendency of most substances to become associated on cooling.^[13]

Similar arguments could be used to describe the effects of pressure on viscosity, where it may be assumed that the viscosity is chiefly a function of the volume for liquids with a finite compressibility. An increasing viscosity with rise of pressure is therefore expected. In addition, if the volume is expanded by heat but reduced again by pressure, the viscosity remains the same.

The local tendency to orientation of molecules in small groups lends the liquid (as referred to previously) a certain degree of association. This association results in a considerable "internal pressure" within a liquid, which is due almost entirely to those molecules which, on account of their temporary low velocities (following the Maxwell distribution) have coalesced with other molecules. The internal pressure between several such molecules might correspond to that between a group of molecules in the solid form.

References[link]

v t e States of matter Solid Liquid Gas / Vapor Plasma Low energy Bose–Einstein condensate · Fermionic condensate · Quantum Hall · Rydberg matter · Strange matter · Superfluid · Supersolid High energy Degenerate matter · QCD matter · Quark–gluon plasma  · Supercritical fluid Other states Colloid · Glass · Liquid crystal · Magnetically ordered (Antiferromagnet, Ferrimagnet, Ferromagnet) · String-net liquid · Superglass Transitions Boiling · Boiling point · Condensation · Critical line · Critical point · Crystallization · Deionization · Deposition · Evaporation · Flash evaporation · Freezing · Ionization · Lambda point · Melting · Melting point · Regelation · Saturated fluid · Sublimation · Supercooling · Triple point · Vaporization Quantities Enthalpy of fusion · Enthalpy of sublimation · Enthalpy of vaporization · Latent heat · Latent internal energy · Trouton's ratio · Volatility Concepts Binodal · Compressed fluid · Cooling curve · Equation of state · Leidenfrost effect · Mpemba effect · Order and disorder (physics) · Spinodal · Superconductivity · Superheated vapor · Superheating · Thermo-dielectric effect

This biographical article needs additional citations for verification. Please help by adding reliable sources. Contentious material about living persons that is unsourced or poorly sourced must be removed immediately, especially if potentially libelous or harmful. (May 2012)

Caro Emerald
Emerald singing in Broek op Langedijk, Netherlands
Background information
Birth name	Caroline Esmeralda van der Leeuw
Born	(1981-04-26) 26 April 1981 (age 31) Amsterdam, Netherlands
Genres	Jazz, easy listening
Occupations	Musician
Instruments	Vocals
Years active	2007-present
Labels	Grandmono Records
Website	www.caroemerald.com

Caroline Esmeralda van der Leeuw (b. 26 April 1981 in Amsterdam), best known by her stage name, Caro Emerald, is a Dutch jazz singer. She debuted on 6 July 2009 with her single "Back It Up". Her debut album Deleted Scenes from the Cutting Room Floor set a new all-time chart record on 20 August 2010, spending its 30th week at number one on the Dutch album chart, beating the previous record set by Michael Jackson's Thriller by one week.^[1] The album has become the biggest selling album of 2010 in the Netherlands, selling over 300,000 copies so far. In total more than a million copies have been sold so far. On 3 October 2010, Van der Leeuw was awarded the Dutch Music Prize "Edison Award" for Best Female Artist.^[2]

Biography[link]

Caroline Esmeralda van der Leeuw was born on 26 April 1981 in Amsterdam, the Netherlands.^[3] She was trained as a jazz vocalist at the Amsterdam Conservatory, graduating in 2005.

Music career[link]

In early 2007 Dutch producer Jan van Wieringen invited van der Leeuw to sing the vocal on a demo track he was co-producing with songwriter/producer David Schreurs. The song, "Back It Up", had been written by Schreurs together with Canadian songwriter Vince Degiorgio, and was based on a hip-hop beat created by Jan and Robin Veldman. Caro's jazzy vocal style was considered a "perfect match" for the new song.^[4]

The song demo was pitched to various publishers and labels but although the reaction was positive they struggled to imagine it suiting any particular artist and didn't believe it had a strong enough chart potential.^[4] In the meantime, however, the song was posted on YouTube reaching public notice around the world. Radio stations picked it up, and the song gained popularity.

When Degiorgio, Schreurs, and van Wieringen discovered van der Leeuw's sound had such potential, they set about working on a full album presenting Caro Emerald as the star in the summer of 2008 and used "Back It Up"'s mix of 40s-50s jazz, easy listening, orchestral Latin, combined with infectious beats as a model.^[4] Adopting a sample based approach but with live instrumentation, the writing sessions drew from a wide range of influences including jazz organist Jackie Davis, exotica composer Martin Denny, mambo king Perez Prado, 20s/30s jazz and van der Leeuw's own vocal inspirations of The Andrews Sisters, Billie Holiday and Sarah Vaughan.^[4] The usual method would be for Schreurs to produce the backing tracks at home and then get together with top line writer and lyricist Degiorgio to write the song. Van der Leeuw would occasionally pitch in her own melody and lyrical ideas, and Van Wieringen co-created the tracks for "The Other Woman" and "Dr Wanna Do".^[4]

After the record labels they approached failed to sign van der Leeuw, Schreurs, van Wieringen and van der Leeuw created their own label Grandmono Records and released "Back It Up" as the first single on 6 July 2009. It was an instant hit and listed in the Dutch Top 40 for 12 weeks, peaking at #12. Kraak & Smaak provided a remix of the song. "Back It Up" was the most played song on Dutch radio station 3FM in 2009.^[5]. Follow up A Night Like This became a #1 hit in The Netherlands.

In 2011 Emerald recorded a version of Brook Benton's 1963 hit "You're All I Want for Christmas", sampling the original song to produce a duet with Benton, who died in 1988. The song was released in December 2011.^[6]

On New Years Eve 2011/2012 Emerald appeared on BBC Two television on the Jools Holland Hootenanny show backed by the Jools Holland Rhythm & Blues Orchestra.

Early 2012, Caro Emerald won two prestigious German awards: a Goldene Kamera for Best Musik International and an Echo Award for Best Newcomer International, beating out other Echo nominees who included Lana Del Rey, Gotye, and LMFAO.

Debut album[link]

Emerald singing in the Netherlands on 9 July 2010

Van der Leeuw's debut album Deleted Scenes from the Cutting Room Floor was released on 29 January 2010 and immediately occupied the number 1 position of the Dutch Album Top 100 charts. On 20 August 2010, the album had been number 1 for 27 weeks, an all time record, beating Michael Jackson's Thriller, which spent 26 weeks at number one in 1983.^[1] The album reached double platinum status in the Netherlands on 5 July 2010.^[7] In August 2010 it reached triple platinum.^[1], in November 2010 four times platinum (200.000)^[8] and in december 2011, six platinum (over 300.000 albums sold). Deleted Scenes From The Cutting Room Floor spent 104 weeks in the official Album charts, until it was removed due to a Dutch chart rule which provided that albums can't spend more than 2 years in the charts.

The second single from the album was "A Night like This". The song was listed in the Dutch Top 40 for 26 weeks and peaked at number 2. In the national single charts, the song peaked at number 1. It was the most played song in The Netherlands in 2010.

The cinematic and upbeat sound of the album has resulted in frequent use of the songs in TV series and advertising campaigns around the world. "A Night Like This" featured in the trailer campaign of NBC series The Playboy Club, a brand campaign by Martini, the trailer of 2 Days in New York (starring Chris Rock and Julie Delpy), and The Secret Circle, amongst others. "Back it Up" featured in a TV ad for Wind Mobile. "That Man" featured in Dancing with the Stars, The Vampire Diaries, a UK advertising campaign for Sky TV, and has been incorporated in the original score of the Disney Nature film Chimpanzee.

On 15 January 2011, she won the Popprijs 2010 for best Dutch pop act of 2010.^{[citation needed]} Also in 2011, the album was released throughout Europe with great commercial success. Deleted Scenes From The Cutting Room Floor became a hit in the UK (1x platinum with sales exceeding 360.000, 8 weeks top 10 peaking at #4), Germany (1x platinum with sales exceeding 280.000, peaking at #5 and Platinum single for A Night Like This with sales exceeding 340.000), Poland (6x platinum), Italy (Gold Single for "Back it Up"), abd Austria (#1 with A Night Like This) In the UK, all 6 singles and even the entire album were A-listed by radio station BBC2. Over 1.000.000 albums have been sold worldwide (certified IFPI Platinum).^{[citation needed]} Due to it's exceptional success, the album was included in an episode of the Dutch version of Classic Albums in April 2012.^{[clarification needed]} In May 2012, Emerald was offered a contract record by Universal Music Group in the USA.

Awards[link]

• 11 April 2010: 3FM Serious Talent Award
• April 15, 2010: Schaal van Rigter
• April 26, 2010: De Eerste Prijs
• Oktober 3, 2010: Edison Best female singer
• MTV EMA Award for best Dutch and Belgian Act.
• January 12, 2011: European Border Breakers Award 2011
• January 15, 2011: 3FM Mega Award 2010
• January 15, 2011: Popprijs 2010
• March 3, 2011: Zilveren Harp 2010
• March 3, 2011: Het Beste Nederlandse lied 2010 (Best song of the year 2010)
• March 14, 2011: 3FM Awards: Best Album and Beste Female Singer
• June 12, 2011: TMF Award for best female
• Februari 4, 2012: Goldene Kamera 2012 Best Music International
• March 2012, Echo (music award) Award Best International Newcomer

^{[9][10][11][12][13][14]}

Discography[link]

Albums[link]

Singles[link]

References[link]

External links[link]

Wikimedia Commons has media related to: Caro Emerald

• Official website
• Official Uvumi Profile
• Caro Emerald Profile and Discography on This is Vintage Now