Phases - Gas, liquid and solid
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A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a nearly constant volume independent of pressure. As such, it is one of the four fundamental states of matter the others being solid, gas, and plasmaand is the only state with a definite volume but no fixed shape. A liquid is made up of tiny vibrating particles of matter, such as atoms, held together by intermolecular bonds.
Water is, by far, density of gases and liquids are both called most common liquid on Earth. Like a gas, a liquid is able to flow and take the shape of a container. Most liquids resist compression, although 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 tensionleading 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. Most known matter in the universe is in gaseous form with traces of detectable solid matter as interstellar clouds or in plasma form within stars. Liquid is one of the four primary states of matterwith the others being solid, gas and plasma. 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. If liquid is placed in a bag, it can be squeezed into any shape. Unlike a gas, a liquid is nearly incompressible, density of gases and liquids are both called that it occupies nearly a constant volume over a wide range of pressures; it does not generally expand to fill available space in a container but forms its own surface, and it may not always mix readily with another liquid.
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 density of gases and liquids are both called 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 pointthe 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. Only two elements are liquid at standard conditions for temperature and pressure: Four more elements have melting points slightly above room temperature: 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. Density of gases and liquids are both called liquids include water, magma, inorganic nonaqueous solvents and many acids.
Important everyday liquids include aqueous solutions like household bleachother mixtures of different substances such as mineral oil and gasoline, emulsions like vinaigrette or mayonnaisesuspensions like blood, and colloids like paint and milk. Many gases can be density of gases and liquids are both called by cooling, producing liquids such as liquid oxygenliquid nitrogenliquid 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. Some materials cannot be classified within the classical three states of matter; they possess solid-like and liquid-like properties. Examples include liquid crystalsused in LCD displays, and biological membranes. Liquids have a variety of uses, as lubricants, solvents, and coolants.
In hydraulic systems, liquid is used to transmit power. In tribologyliquids 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 boxesmetalworkingand hydraulic systems for their good lubrication properties.
Many liquids are used as solventsto dissolve other liquids or solids. Solutions are found in a wide variety of applications, including paintssealantsand adhesives. Naphtha 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, inksand liquid dye lasers. They are used in the food industry, in processes such as the extraction of vegetable oil.
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 exchangersuch as a radiatoror the heat can be removed with the liquid during evaporation.
During perspirationsweat removes heat from the human body by evaporating. In the heating, ventilation, and air-conditioning industry HVACliquids such as water are used to transfer heat from one area to another. 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 pumpswhich transmit this force to hydraulic cylinders. Hydraulics can be found in many applications, such as automotive brakes and transmissionsheavy equipmentand airplane control systems.
Various hydraulic presses are used extensively in repair and manufacturing, for lifting, pressing, clamping and forming. Liquids are sometimes used in measuring devices. A thermometer often uses the thermal expansion of liquids, such as mercurycombined with their ability to flow to indicate temperature. A manometer uses the weight of density of gases and liquids are both called liquid to indicate air pressure. Quantities of liquids are measured in units of volume. The volume of a quantity of liquid is fixed by its temperature and pressure.
Liquids generally expand when heated, and contract when cooled. Liquids have little compressibility. Water, for example, will compress by only This incompressible nature makes a liquid suitable for transmitting hydraulic power, because very little of the energy is lost in the form of compression. The banging of pipes, called water hammeroccurs when a valve is suddenly closed, creating a huge pressure-spike at the valve that travels backward through the system at just under the speed of sound.
Another phenomenon caused by liquid's incompressibility is cavitation. Because liquids have little elasticity density of gases and liquids are both called can literally be pulled apart in areas of high turbulence or a dramatic change in direction, such as the trailing edge of a boat propeller or a sharp corner in a pipe. A liquid in an area of low pressure vacuum vaporizes and forms bubbles, which then collapse as they enter high pressure areas. This causes liquid to fill the cavities left by the bubbles with tremendous localized force, eroding any adjacent solid surface.
In a gravitational fieldliquids 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, pat any depth, zis given by. 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 density of gases and liquids are both called fluids, but is especially strong in liquids due to their high density.
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 density of gases and liquids are both called of drops and bubbles.
Surface wavescapillary actionwettingand ripples are other consequences of surface tension. In a confined liquiddefined by geometric constraints on a nanoscopic scale, most molecules sense some surface effects, which can result in physical properties grossly deviating from those of the bulk liquid. A free surface is the surface of a fluid that is subject to both zero perpendicular normal stress and parallel shear stress, such as the boundary between, e.
The liquid level as in, e. It may be measured with a level sensor. Viscosity measures the resistance of a liquid which is being deformed by either shear stress [14] or extensional stress. When a liquid is supercooled towards the glass transitionthe 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.
At a temperature below the boiling pointany 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 crystallizechanging 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.
For the opposite transition from solid to liquid, see melting. Density of gases and liquids are both called phase diagram explains why liquids do not exist in space or any other vacuum.
