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One of the four phases of matter, a liquid is a fluid whose volume is fixed under conditions of constant temperature and pressure; and, whose shape is usually determined by the container it fills. Furthermore, liquids exert pressure on the sides of a container as well as on anything within the liquid itself; this pressure is transmitted undiminished in all directions.If a liquid is at rest in a uniform gravitational field, the pressure at any point is given by
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where is the density of the liquid (assumed constant) and is the depth of the point below the surface. Note that this formula assumes that the pressure at the free surface is zero.
Liquids have traits of surface tension and capillarity; they generally expand when heated, and contract when cooled. Objects immersed in liquids are subject to the phenomenon of buoyancy.
Liquids at their respective boiling point change to gases, and at their freezing points, change to a solids. Via fractional distillation, liquids can be separated from one another as they vaporise at their own individual boiling points. Cohesion between moleculeIn science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. A molecule consists of multiple atoms joined by shared pairs of electrons in a covalent bond''. It may consist of atoms of liquid is insufficient to prevent those at free surface from evaporatingEvaporation is the process whereby atoms or molecules in a liquid state (or solid state if the substance sublimes) gain sufficient energy to enter the gaseous state. The thermal motion of a molecule must be sufficient to overcome the surface tension of th.
It should be noted that glassFor eyeglasses, see spectacles The physics definition of a glass is a uniform amorphous solid material, usually produced when a suitably viscous molten material cools very rapidly, thereby not giving enough time for a regular crystal lattice to form. at normal temperatures is not a "supercooled liquid", but a solid. See the article on glass for more details.
1 See also
- Other phases of matter: solid, gas, and plasmaFor the fluid portion of blood, see blood plasma; also, other uses. There is debate as to whether plasma is an individual state of matter or simply a type of gas. In physics and chemistry, plasma (also called an ionised gas is an energetic gas-phase state
- rippleIn physics, ripple s are surface waves on a liquid with wavelengths so short that the liquid's motion is governed almost entirely by surface tension forces. The wavelength of a ripple must be less than :λ 2π√(γ/ρg) where γ
- specific gravity
2 Other uses
Liquid may also refer to—
Chemistry
Condensed matter physics
