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123-444: Gas is one of the four fundamental states of matter . The others are solid , liquid , and plasma . A pure gas may be made up of individual atoms (e.g. a noble gas like neon ), elemental molecules made from one type of atom (e.g. oxygen ), or compound molecules made from a variety of atoms (e.g. carbon dioxide ). A gas mixture , such as air , contains a variety of pure gases. What distinguishes gases from liquids and solids
246-647: A body-centred cubic structure at temperatures below 912 °C (1,674 °F), and a face-centred cubic structure between 912 and 1,394 °C (2,541 °F). Ice has fifteen known crystal structures, or fifteen solid phases, which exist at various temperatures and pressures. Glasses and other non-crystalline, amorphous solids without long-range order are not thermal equilibrium ground states; therefore they are described below as nonclassical states of matter. Solids can be transformed into liquids by melting, and liquids can be transformed into solids by freezing. Solids can also change directly into gases through
369-452: A combustion chamber of a jet engine . It may also be useful to keep the elementary reactions and chemical dissociations for calculating emissions . Each one of the assumptions listed below adds to the complexity of the problem's solution. As the density of a gas increases with rising pressure, the intermolecular forces play a more substantial role in gas behavior which results in the ideal gas law no longer providing "reasonable" results. At
492-414: A glass transition when heated towards the liquid state. Glasses can be made of quite different classes of materials: inorganic networks (such as window glass, made of silicate plus additives), metallic alloys, ionic melts , aqueous solutions , molecular liquids, and polymers . Thermodynamically, a glass is in a metastable state with respect to its crystalline counterpart. The conversion rate, however,
615-591: A liceo (high school) in Vercelli , where his family lived and had some property. In 1811, he published an article with the title Essai d'une manière de déterminer les masses relatives des molécules élémentaires des corps, et les proportions selon lesquelles elles entrent dans ces combinaisons ("Essay on a manner of Determining the Relative Masses of the Elementary Molecules of Bodies and
738-453: A magnetic domain ). If the domains are also aligned, the solid is a permanent magnet , which is magnetic even in the absence of an external magnetic field . The magnetization disappears when the magnet is heated to the Curie point , which for iron is 768 °C (1,414 °F). An antiferromagnet has two networks of equal and opposite magnetic moments, which cancel each other out so that
861-420: A phase transition . Water can be said to have several distinct solid states. The appearance of superconductivity is associated with a phase transition, so there are superconductive states. Likewise, ferromagnetic states are demarcated by phase transitions and have distinctive properties. When the change of state occurs in stages the intermediate steps are called mesophases . Such phases have been exploited by
984-439: A chemical equation, the state of matter of the chemicals may be shown as (s) for solid, (l) for liquid, and (g) for gas. An aqueous solution is denoted (aq), for example, Matter in the plasma state is seldom used (if at all) in chemical equations, so there is no standard symbol to denote it. In the rare equations that plasma is used it is symbolized as (p). Glass is a non-crystalline or amorphous solid material that exhibits
1107-538: A comprehensive listing of these exotic states of matter, see list of states of matter . The only chemical elements that are stable diatomic homonuclear molecular gases at STP are hydrogen (H 2 ), nitrogen (N 2 ), oxygen (O 2 ), and two halogens : fluorine (F 2 ) and chlorine (Cl 2 ). When grouped with the monatomic noble gases – helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) – these gases are referred to as "elemental gases". The word gas
1230-425: A container of gas, the term pressure (or absolute pressure) refers to the average force per unit area that the gas exerts on the surface of the container. Within this volume, it is sometimes easier to visualize the gas particles moving in straight lines until they collide with the container (see diagram at top). The force imparted by a gas particle into the container during this collision is the change in momentum of
1353-415: A corresponding change in kinetic energy . For example: Imagine you have a sealed container of a fixed-size (a constant volume), containing a fixed-number of gas particles; starting from absolute zero (the theoretical temperature at which atoms or molecules have no thermal energy, i.e. are not moving or vibrating), you begin to add energy to the system by heating the container, so that energy transfers to
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#17328011744171476-573: A gas can be calculated from the mass of a sample of known volume. Avogadro developed this hypothesis after Joseph Louis Gay-Lussac published his law on volumes (and combining gases) in 1808. The greatest problem Avogadro had to resolve was the confusion at that time regarding atoms and molecules. One of his most important contributions was clearly distinguishing one from the other, stating that gases are composed of molecules, and these molecules are composed of atoms. (For instance, John Dalton did not consider this possibility.) Avogadro did not actually use
1599-408: A given liquid can exist is its critical temperature . A gas is a compressible fluid. Not only will a gas conform to the shape of its container but it will also expand to fill the container. In a gas, the molecules have enough kinetic energy so that the effect of intermolecular forces is small (or zero for an ideal gas ), and the typical distance between neighboring molecules is much greater than
1722-472: A greater number of particles (transition from gas to plasma ). Finally, all of the thermodynamic processes were presumed to describe uniform gases whose velocities varied according to a fixed distribution. Using a non-equilibrium situation implies the flow field must be characterized in some manner to enable a solution. One of the first attempts to expand the boundaries of the ideal gas law was to include coverage for different thermodynamic processes by adjusting
1845-405: A heavier analogue of the common down quark . It may be stable at lower energy states once formed, although this is not known. Quark–gluon plasma is a very high-temperature phase in which quarks become free and able to move independently, rather than being perpetually bound into particles, in a sea of gluons , subatomic particles that transmit the strong force that binds quarks together. This
1968-518: A liquid (or solid), in which case the gas pressure equals the vapor pressure of the liquid (or solid). A supercritical fluid (SCF) is a gas whose temperature and pressure are above the critical temperature and critical pressure respectively. In this state, the distinction between liquid and gas disappears. A supercritical fluid has the physical properties of a gas, but its high density confers solvent properties in some cases, which leads to useful applications. For example, supercritical carbon dioxide
2091-440: A liquid at its melting point , boils into a gas at its boiling point , and if heated high enough would enter a plasma state in which the electrons are so energized that they leave their parent atoms. Forms of matter that are not composed of molecules and are organized by different forces can also be considered different states of matter. Superfluids (like Fermionic condensate ) and the quark–gluon plasma are examples. In
2214-494: A liquid, but exhibiting long-range order. For example, the nematic phase consists of long rod-like molecules such as para-azoxyanisole , which is nematic in the temperature range 118–136 °C (244–277 °F). In this state the molecules flow as in a liquid, but they all point in the same direction (within each domain) and cannot rotate freely. Like a crystalline solid, but unlike a liquid, liquid crystals react to polarized light. Other types of liquid crystals are described in
2337-470: A number of much more accurate equations of state have been developed for gases in specific temperature and pressure ranges. The "gas models" that are most widely discussed are "perfect gas", "ideal gas" and "real gas". Each of these models has its own set of assumptions to facilitate the analysis of a given thermodynamic system. Each successive model expands the temperature range of coverage to which it applies. The equation of state for an ideal or perfect gas
2460-582: A phenomenon known as the Meissner effect or perfect diamagnetism . Superconducting magnets are used as electromagnets in magnetic resonance imaging machines. The phenomenon of superconductivity was discovered in 1911, and for 75 years was only known in some metals and metallic alloys at temperatures below 30 K. In 1986 so-called high-temperature superconductivity was discovered in certain ceramic oxides, and has now been observed in temperatures as high as 164 K. Close to absolute zero, some liquids form
2583-438: A second liquid state described as superfluid because it has zero viscosity (or infinite fluidity; i.e., flowing without friction). This was discovered in 1937 for helium , which forms a superfluid below the lambda temperature of 2.17 K (−270.98 °C; −455.76 °F). In this state it will attempt to "climb" out of its container. It also has infinite thermal conductivity so that no temperature gradient can form in
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#17328011744172706-479: A solid can only increase its internal energy by exciting additional vibrational modes, as the crystal lattice structure prevents both translational and rotational motion. These heated gas molecules have a greater speed range (wider distribution of speeds) with a higher average or mean speed. The variance of this distribution is due to the speeds of individual particles constantly varying, due to repeated collisions with other particles. The speed range can be described by
2829-430: A string-net liquid, atoms have apparently unstable arrangement, like a liquid, but are still consistent in overall pattern, like a solid. When in a normal solid state, the atoms of matter align themselves in a grid pattern, so that the spin of any electron is the opposite of the spin of all electrons touching it. But in a string-net liquid, atoms are arranged in some pattern that requires some electrons to have neighbors with
2952-481: A superdense conglomeration of neutrons. Normally free neutrons outside an atomic nucleus will decay with a half life of approximately 10 minutes, but in a neutron star, the decay is overtaken by inverse decay. Cold degenerate matter is also present in planets such as Jupiter and in the even more massive brown dwarfs , which are expected to have a core with metallic hydrogen . Because of the degeneracy, more massive brown dwarfs are not significantly larger. In metals,
3075-467: A superfluid. Placing a superfluid in a spinning container will result in quantized vortices . These properties are explained by the theory that the common isotope helium-4 forms a Bose–Einstein condensate (see next section) in the superfluid state. More recently, fermionic condensate superfluids have been formed at even lower temperatures by the rare isotope helium-3 and by lithium-6 . In 1924, Albert Einstein and Satyendra Nath Bose predicted
3198-423: A system at equilibrium. 1000 atoms a gas occupy the same space as any other 1000 atoms for any given temperature and pressure. This concept is easier to visualize for solids such as iron which are incompressible compared to gases. However, volume itself --- not specific --- is an extensive property. The symbol used to represent density in equations is ρ (rho) with SI units of kilograms per cubic meter. This term
3321-417: A uniform liquid. Transition metal atoms often have magnetic moments due to the net spin of electrons that remain unpaired and do not form chemical bonds. In some solids the magnetic moments on different atoms are ordered and can form a ferromagnet, an antiferromagnet or a ferrimagnet. In a ferromagnet —for instance, solid iron —the magnetic moment on each atom is aligned in the same direction (within
3444-790: A variety of gases in various settings. Their detailed studies ultimately led to a mathematical relationship among these properties expressed by the ideal gas law (see § Ideal and perfect gas section below). Gas particles are widely separated from one another, and consequently, have weaker intermolecular bonds than liquids or solids. These intermolecular forces result from electrostatic interactions between gas particles. Like-charged areas of different gas particles repel, while oppositely charged regions of different gas particles attract one another; gases that contain permanently charged ions are known as plasmas . Gaseous compounds with polar covalent bonds contain permanent charge imbalances and so experience relatively strong intermolecular forces, although
3567-425: Is a combination of a finite set of possible motions including translation, rotation, and vibration . This finite range of possible motions, along with the finite set of molecules in the system, leads to a finite number of microstates within the system; we call the set of all microstates an ensemble . Specific to atomic or molecular systems, we could potentially have three different kinds of ensemble, depending on
3690-442: Is a disordered state in a system of interacting quantum spins which preserves its disorder to very low temperatures, unlike other disordered states. It is not a liquid in physical sense, but a solid whose magnetic order is inherently disordered. The name "liquid" is due to an analogy with the molecular disorder in a conventional liquid. A QSL is neither a ferromagnet , where magnetic domains are parallel, nor an antiferromagnet , where
3813-399: Is a type of matter theorized to exist in atomic nuclei traveling near the speed of light. According to Einstein's theory of relativity, a high-energy nucleus appears length contracted, or compressed, along its direction of motion. As a result, the gluons inside the nucleus appear to a stationary observer as a "gluonic wall" traveling near the speed of light. At very high energies, the density of
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3936-419: Is analogous to the liberation of electrons from atoms in a plasma. This state is briefly attainable in extremely high-energy heavy ion collisions in particle accelerators , and allows scientists to observe the properties of individual quarks. Theories predicting the existence of quark–gluon plasma were developed in the late 1970s and early 1980s, and it was detected for the first time in the laboratory at CERN in
4059-536: Is assumed that essentially all electrons are "free", and that a very high-energy plasma is essentially bare nuclei swimming in a sea of electrons. This forms the so-called fully ionised plasma. The plasma state is often misunderstood, and although not freely existing under normal conditions on Earth, it is quite commonly generated by either lightning , electric sparks , fluorescent lights , neon lights or in plasma televisions . The Sun's corona , some types of flame , and stars are all examples of illuminated matter in
4182-415: Is no long-range magnetic order. Superconductors are materials which have zero electrical resistivity , and therefore perfect conductivity. This is a distinct physical state which exists at low temperature, and the resistivity increases discontinuously to a finite value at a sharply-defined transition temperature for each superconductor. A superconductor also excludes all magnetic fields from its interior,
4305-421: Is possible for a single compound to form different phases that are in the same state of matter. For example, ice is the solid state of water, but there are multiple phases of ice with different crystal structures , which are formed at different pressures and temperatures. In a solid, constituent particles (ions, atoms, or molecules) are closely packed together. The forces between particles are so strong that
4428-446: Is practically zero. A plastic crystal is a molecular solid with long-range positional order but with constituent molecules retaining rotational freedom; in an orientational glass this degree of freedom is frozen in a quenched disordered state. Similarly, in a spin glass magnetic disorder is frozen. Liquid crystal states have properties intermediate between mobile liquids and ordered solids. Generally, they are able to flow like
4551-405: Is referred to as compressibility . Like pressure and temperature, density is a state variable of a gas and the change in density during any process is governed by the laws of thermodynamics. For a static gas , the density is the same throughout the entire container. Density is therefore a scalar quantity . It can be shown by kinetic theory that the density is inversely proportional to the size of
4674-414: Is the ideal gas law and reads where P is the pressure, V is the volume, n is amount of gas (in mol units), R is the universal gas constant , 8.314 J/(mol K), and T is the temperature. Written this way, it is sometimes called the "chemist's version", since it emphasizes the number of molecules n . It can also be written as where R s {\displaystyle R_{s}}
4797-414: Is the reciprocal of specific volume. Since gas molecules can move freely within a container, their mass is normally characterized by density. Density is the amount of mass per unit volume of a substance, or the inverse of specific volume. For gases, the density can vary over a wide range because the particles are free to move closer together when constrained by pressure or volume. This variation of density
4920-404: Is the key to connection between the microscopic states of a system and the macroscopic variables which we can measure, such as temperature, pressure, heat capacity, internal energy, enthalpy, and entropy, just to name a few. ( Read : Partition function Meaning and significance ) Using the partition function to find the energy of a molecule, or system of molecules, can sometimes be approximated by
5043-403: Is the reason why modeling a "real gas" is more mathematically difficult than an " ideal gas". Ignoring these proximity-dependent forces allows a real gas to be treated like an ideal gas , which greatly simplifies calculation. The intermolecular attractions and repulsions between two gas molecules depend on the distance between them. The combined attractions and repulsions are well-modelled by
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5166-426: Is the specific gas constant for a particular gas, in units J/(kg K), and ρ = m/V is density. This notation is the "gas dynamicist's" version, which is more practical in modeling of gas flows involving acceleration without chemical reactions. The ideal gas law does not make an assumption about the heat capacity of a gas. In the most general case, the specific heat is a function of both temperature and pressure. If
5289-555: Is the vast separation of the individual gas particles . This separation usually makes a colorless gas invisible to the human observer. The gaseous state of matter occurs between the liquid and plasma states, the latter of which provides the upper-temperature boundary for gases. Bounding the lower end of the temperature scale lie degenerative quantum gases which are gaining increasing attention. High-density atomic gases super-cooled to very low temperatures are classified by their statistical behavior as either Bose gases or Fermi gases . For
5412-413: Is typical to speak of intensive and extensive properties . Properties which depend on the amount of gas (either by mass or volume) are called extensive properties, while properties that do not depend on the amount of gas are called intensive properties. Specific volume is an example of an intensive property because it is the ratio of volume occupied by a unit of mass of a gas that is identical throughout
5535-421: Is typical to specify a frame of reference or length scale . A larger length scale corresponds to a macroscopic or global point of view of the gas. This region (referred to as a volume) must be sufficient in size to contain a large sampling of gas particles. The resulting statistical analysis of this sample size produces the "average" behavior (i.e. velocity, temperature or pressure) of all the gas particles within
5658-478: Is used to extract caffeine in the manufacture of decaffeinated coffee. A gas is usually converted to a plasma in one of two ways, either from a huge voltage difference between two points, or by exposing it to extremely high temperatures. Heating matter to high temperatures causes electrons to leave the atoms, resulting in the presence of free electrons. This creates a so-called partially ionised plasma. At very high temperatures, such as those present in stars, it
5781-597: The Equipartition theorem , which greatly-simplifies calculation. However, this method assumes all molecular degrees of freedom are equally populated, and therefore equally utilized for storing energy within the molecule. It would imply that internal energy changes linearly with temperature, which is not the case. This ignores the fact that heat capacity changes with temperature, due to certain degrees of freedom being unreachable (a.k.a. "frozen out") at lower temperatures. As internal energy of molecules increases, so does
5904-542: The Lennard-Jones potential , which is one of the most extensively studied of all interatomic potentials describing the potential energy of molecular systems. Due to the general applicability and importance, the Lennard-Jones model system is often referred to as 'Lennard-Jonesium'. The Lennard-Jones potential between molecules can be broken down into two separate components: a long-distance attraction due to
6027-601: The London dispersion force , and a short-range repulsion due to electron-electron exchange interaction (which is related to the Pauli exclusion principle ). When two molecules are relatively distant (meaning they have a high potential energy), they experience a weak attracting force, causing them to move toward each other, lowering their potential energy. However, if the molecules are too far away, then they would not experience attractive force of any significance. Additionally, if
6150-475: The Maxwell–Boltzmann distribution . Use of this distribution implies ideal gases near thermodynamic equilibrium for the system of particles being considered. The symbol used to represent specific volume in equations is "v" with SI units of cubic meters per kilogram. The symbol used to represent volume in equations is "V" with SI units of cubic meters. When performing a thermodynamic analysis, it
6273-576: The University of Colorado at Boulder , produced the first such condensate experimentally. A Bose–Einstein condensate is "colder" than a solid. It may occur when atoms have very similar (or the same) quantum levels , at temperatures very close to absolute zero , −273.15 °C (−459.67 °F). A fermionic condensate is similar to the Bose–Einstein condensate but composed of fermions . The Pauli exclusion principle prevents fermions from entering
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#17328011744176396-466: The baryon asymmetry in the universe, but little is known about it. In string theory , a Hagedorn temperature is predicted for superstrings at about 10 K, where superstrings are copiously produced. At Planck temperature (10 K), gravity becomes a significant force between individual particles. No current theory can describe these states and they cannot be produced with any foreseeable experiment. However, these states are important in cosmology because
6519-458: The compressibility factor Z is set to 1 meaning that this pneumatic ratio remains constant. A compressibility factor of one also requires the four state variables to follow the ideal gas law . This approximation is more suitable for applications in engineering although simpler models can be used to produce a "ball-park" range as to where the real solution should lie. An example where the "ideal gas approximation" would be suitable would be inside
6642-411: The macroscopic properties of pressure and volume of a gas. His experiment used a J-tube manometer which looks like a test tube in the shape of the letter J. Boyle trapped an inert gas in the closed end of the test tube with a column of mercury , thereby making the number of particles and the temperature constant. He observed that when the pressure was increased in the gas, by adding more mercury to
6765-438: The "Bose–Einstein condensate" (BEC), sometimes referred to as the fifth state of matter. In a BEC, matter stops behaving as independent particles, and collapses into a single quantum state that can be described with a single, uniform wavefunction. In the gas phase, the Bose–Einstein condensate remained an unverified theoretical prediction for many years. In 1995, the research groups of Eric Cornell and Carl Wieman , of JILA at
6888-726: The French-American historian Jacques Barzun speculated that Van Helmont had borrowed the word from the German Gäscht , meaning the froth resulting from fermentation . Because most gases are difficult to observe directly, they are described through the use of four physical properties or macroscopic characteristics: pressure , volume , number of particles (chemists group them by moles ) and temperature. These four characteristics were repeatedly observed by scientists such as Robert Boyle , Jacques Charles , John Dalton , Joseph Gay-Lussac and Amedeo Avogadro for
7011-507: The Molecules by Which Their Integral Particles Are Made"), but the same indifference was shown to his theory as well. Only through studies by Charles Frédéric Gerhardt and Auguste Laurent on organic chemistry was it possible to demonstrate that Avogadro's law explained why the same quantities of molecules in a gas have the same volume. Unfortunately, related experiments with some inorganic substances showed seeming contradictions. This
7134-512: The Proportions by Which They Enter These Combinations"), which contains Avogadro's hypothesis. Avogadro submitted this essay to Jean-Claude Delamétherie 's Journal de Physique, de Chimie et d'Histoire naturelle ("Journal of Physics, Chemistry and Natural History"). In 1820, he became a professor of physics at the University of Turin . Turin was now the capital of the restored Savoyard Kingdom of Sardinia under Victor Emmanuel I . Avogadro
7257-697: The Relative Masses of Elementary Molecules, or Suggested Densities of Their Gases, and on the Constituents of Some of Their Compounds, As a Follow-up to the Essay on the Same Subject, Published in the Journal of Physics, July 1811") about gas densities. In 1821 he published another paper, Nouvelles considérations sur la théorie des proportions déterminées dans les combinaisons, et sur la détermination des masses des molécules des corps ( New Considerations on
7380-962: The Theory of Proportions Determined in Combinations, and on Determination of the Masses of Atoms ) and shortly afterwards, Mémoire sur la manière de ramener les composès organiques aux lois ordinaires des proportions déterminées ("Note on the Manner of Finding the Organic Composition by the Ordinary Laws of Determined Proportions"). In 1841, he published his work in Fisica dei corpi ponderabili, ossia Trattato della costituzione materiale de' corpi , 4 volumes. The scientific community did not give great attention to Avogadro's theory, and it
7503-407: The ability to store energy within additional degrees of freedom. As more degrees of freedom become available to hold energy, this causes the molar heat capacity of the substance to increase. Brownian motion is the mathematical model used to describe the random movement of particles suspended in a fluid. The gas particle animation, using pink and green particles, illustrates how this behavior results in
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#17328011744177626-417: The above stated effects which cause these attractions and repulsions, real gases , delineate from the ideal gas model by the following generalization: An equation of state (for gases) is a mathematical model used to roughly describe or predict the state properties of a gas. At present, there is no single equation of state that accurately predicts the properties of all gases under all conditions. Therefore,
7749-444: The attractive London-dispersion force. If the two molecules collide, they are moving too fast and their kinetic energy will be much greater than any attractive potential energy, so they will only experience repulsion upon colliding. Thus, attractions between molecules can be neglected at high temperatures due to high speeds. At high temperatures, and high pressures, repulsion is the dominant intermolecular interaction. Accounting for
7872-714: The blocks, block copolymers undergo a similar phase separation. However, because the blocks are covalently bonded to each other, they cannot demix macroscopically as water and oil can, and so instead the blocks form nanometre-sized structures. Depending on the relative lengths of each block and the overall block topology of the polymer, many morphologies can be obtained, each its own phase of matter. Ionic liquids also display microphase separation. The anion and cation are not necessarily compatible and would demix otherwise, but electric charge attraction prevents them from separating. Their anions and cations appear to diffuse within compartmentalized layers or micelles instead of freely as in
7995-429: The column, the trapped gas' volume decreased (this is known as an inverse relationship). Furthermore, when Boyle multiplied the pressure and volume of each observation, the product was constant. This relationship held for every gas that Boyle observed leading to the law, (PV=k), named to honor his work in this field. There are many mathematical tools available for analyzing gas properties. Boyle's lab equipment allowed
8118-488: The compound's net charge remains neutral. Transient, randomly induced charges exist across non-polar covalent bonds of molecules and electrostatic interactions caused by them are referred to as Van der Waals forces . The interaction of these intermolecular forces varies within a substance which determines many of the physical properties unique to each gas. A comparison of boiling points for compounds formed by ionic and covalent bonds leads us to this conclusion. Compared to
8241-410: The container in which a fixed mass of gas is confined. In this case of a fixed mass, the density decreases as the volume increases. If one could observe a gas under a powerful microscope, one would see a collection of particles without any definite shape or volume that are in more or less random motion. These gas particles only change direction when they collide with another particle or with the sides of
8364-466: The container. This microscopic view of gas is well-described by statistical mechanics , but it can be described by many different theories. The kinetic theory of gases , which makes the assumption that these collisions are perfectly elastic , does not account for intermolecular forces of attraction and repulsion. Kinetic theory provides insight into the macroscopic properties of gases by considering their molecular composition and motion. Starting with
8487-478: The definitions of momentum and kinetic energy , one can use the conservation of momentum and geometric relationships of a cube to relate macroscopic system properties of temperature and pressure to the microscopic property of kinetic energy per molecule. The theory provides averaged values for these two properties. The kinetic theory of gases can help explain how the system (the collection of gas particles being considered) responds to changes in temperature, with
8610-507: The distinction is based on qualitative differences in properties. Matter in the solid state maintains a fixed volume (assuming no change in temperature or air pressure) and shape, with component particles ( atoms , molecules or ions ) close together and fixed into place. Matter in the liquid state maintains a fixed volume (assuming no change in temperature or air pressure), but has a variable shape that adapts to fit its container. Its particles are still close together but move freely. Matter in
8733-572: The electrons can be modeled as a degenerate gas moving in a lattice of non-degenerate positive ions. In regular cold matter, quarks , fundamental particles of nuclear matter, are confined by the strong force into hadrons that consist of 2–4 quarks, such as protons and neutrons. Quark matter or quantum chromodynamical (QCD) matter is a group of phases where the strong force is overcome and quarks are deconfined and free to move. Quark matter phases occur at extremely high densities or temperatures, and there are no known ways to produce them in equilibrium in
8856-521: The equation to read pV = constant and then varying the n through different values such as the specific heat ratio , γ . Real gas effects include those adjustments made to account for a greater range of gas behavior: For most applications, such a detailed analysis is excessive. Examples where real gas effects would have a significant impact would be on the Space Shuttle re-entry where extremely high temperatures and pressures were present or
8979-439: The gas system in question, makes it possible to solve such complex dynamic situations as space vehicle reentry. An example is the analysis of the space shuttle reentry pictured to ensure the material properties under this loading condition are appropriate. In this flight situation, the gas is no longer behaving ideally. The symbol used to represent pressure in equations is "p" or "P" with SI units of pascals . When describing
9102-412: The gaseous state has both variable volume and shape, adapting both to fit its container. Its particles are neither close together nor fixed in place. Matter in the plasma state has variable volume and shape, and contains neutral atoms as well as a significant number of ions and electrons , both of which can move around freely. The term phase is sometimes used as a synonym for state of matter, but it
9225-646: The gases produced during geological events as in the image of the 1990 eruption of Mount Redoubt . State of matter In physics , a state of matter is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life: solid , liquid , gas , and plasma . Many intermediate states are known to exist, such as liquid crystal , and some states only exist under extreme conditions, such as Bose–Einstein condensates and Fermionic condensates (in extreme cold), neutron-degenerate matter (in extreme density), and quark–gluon plasma (at extremely high energy ). Historically,
9348-529: The gluons in this wall is seen to increase greatly. Unlike the quark–gluon plasma produced in the collision of such walls, the color-glass condensate describes the walls themselves, and is an intrinsic property of the particles that can only be observed under high-energy conditions such as those at RHIC and possibly at the Large Hadron Collider as well. Various theories predict new states of matter at very high energies. An unknown state has created
9471-430: The gravitational force increases, but pressure does not increase proportionally. Electron-degenerate matter is found inside white dwarf stars. Electrons remain bound to atoms but are able to transfer to adjacent atoms. Neutron-degenerate matter is found in neutron stars . Vast gravitational pressure compresses atoms so strongly that the electrons are forced to combine with protons via inverse beta-decay, resulting in
9594-424: The introduction of liquid crystal technology. The state or phase of a given set of matter can change depending on pressure and temperature conditions, transitioning to other phases as these conditions change to favor their existence; for example, solid transitions to liquid with an increase in temperature. Near absolute zero , a substance exists as a solid . As heat is added to this substance it melts into
9717-490: The laboratory; in ordinary conditions, any quark matter formed immediately undergoes radioactive decay. Strange matter is a type of quark matter that is suspected to exist inside some neutron stars close to the Tolman–Oppenheimer–Volkoff limit (approximately 2–3 solar masses ), although there is no direct evidence of its existence. In strange matter, part of the energy available manifests as strange quarks ,
9840-435: The magnetic domains are antiparallel; instead, the magnetic domains are randomly oriented. This can be realized e.g. by geometrically frustrated magnetic moments that cannot point uniformly parallel or antiparallel. When cooling down and settling to a state, the domain must "choose" an orientation, but if the possible states are similar in energy, one will be chosen randomly. Consequently, despite strong short-range order, there
9963-453: The main article on these states. Several types have technological importance, for example, in liquid crystal displays . Copolymers can undergo microphase separation to form a diverse array of periodic nanostructures, as shown in the example of the styrene-butadiene-styrene block copolymer shown at right. Microphase separation can be understood by analogy to the phase separation between oil and water. Due to chemical incompatibility between
10086-593: The microscopic behavior of molecules in any system, and therefore, are necessary for accurately predicting the physical properties of gases (and liquids) across wide variations in physical conditions. Arising from the study of physical chemistry , one of the most prominent intermolecular forces throughout physics, are van der Waals forces . Van der Waals forces play a key role in determining nearly all physical properties of fluids such as viscosity , flow rate , and gas dynamics (see physical characteristics section). The van der Waals interactions between gas molecules,
10209-447: The molecular size. A gas has no definite shape or volume, but occupies the entire container in which it is confined. A liquid may be converted to a gas by heating at constant pressure to the boiling point , or else by reducing the pressure at constant temperature. At temperatures below its critical temperature , a gas is also called a vapor , and can be liquefied by compression alone without cooling. A vapor can exist in equilibrium with
10332-507: The molecules get too close then they will collide, and experience a very high repulsive force (modelled by Hard spheres ) which is a much stronger force than the attractions, so that any attraction due to proximity is disregarded. As two molecules approach each other, from a distance that is neither too-far, nor too-close, their attraction increases as the magnitude of their potential energy increases (becoming more negative), and lowers their total internal energy. The attraction causing
10455-473: The molecules into close proximity, and raising the pressure, the repulsions will begin to dominate over the attractions, as the rate at which collisions are happening will increase significantly. Therefore, at low temperatures, and low pressures, attraction is the dominant intermolecular interaction. If two molecules are moving at high speeds, in arbitrary directions, along non-intersecting paths, then they will not spend enough time in proximity to be affected by
10578-420: The molecules to get closer, can only happen if the molecules remain in proximity for the duration of time it takes to physically move closer. Therefore, the attractive forces are strongest when the molecules move at low speeds . This means that the attraction between molecules is significant when gas temperatures is low . However, if you were to isothermally compress this cold gas into a small volume, forcing
10701-509: The more exotic operating environments where the gases no longer behave in an "ideal" manner. As gases are subjected to extreme conditions, tools to interpret them become more complex, from the Euler equations for inviscid flow to the Navier–Stokes equations that fully account for viscous effects. This advanced math, including statistics and multivariable calculus , adapted to the conditions of
10824-471: The net magnetization is zero. For example, in nickel(II) oxide (NiO), half the nickel atoms have moments aligned in one direction and half in the opposite direction. In a ferrimagnet , the two networks of magnetic moments are opposite but unequal, so that cancellation is incomplete and there is a non-zero net magnetization. An example is magnetite (Fe 3 O 4 ), which contains Fe and Fe ions with different magnetic moments. A quantum spin liquid (QSL)
10947-526: The number of molecules per mole of a substance is named the Avogadro constant , N A . It is exactly 6.022 140 76 × 10 mol . The Avogadro constant is used to compute the results of chemical reactions. It allows chemists to determine the amounts of substances produced in a given reaction to a great degree of accuracy. Johann Josef Loschmidt first calculated the value of the Avogadro constant,
11070-533: The number of particles in one mole, sometimes referred to as the Loschmidt number in German-speaking countries ( Loschmidt constant now has another meaning). Avogadro's law states that the relationship between the masses of the same volume of all gases (at the same temperature and pressure) corresponds to the relationship between their respective molecular weights. Hence, the relative molecular mass of
11193-514: The other states of matter, gases have low density and viscosity . Pressure and temperature influence the particles within a certain volume. This variation in particle separation and speed is referred to as compressibility . This particle separation and size influences optical properties of gases as can be found in the following list of refractive indices . Finally, gas particles spread apart or diffuse in order to homogeneously distribute themselves throughout any container. When observing gas, it
11316-421: The particle. During a collision only the normal component of velocity changes. A particle traveling parallel to the wall does not change its momentum. Therefore, the average force on a surface must be the average change in linear momentum from all of these gas particle collisions. Pressure is the sum of all the normal components of force exerted by the particles impacting the walls of the container divided by
11439-519: The particle. The particle (generally consisting of millions or billions of atoms) thus moves in a jagged course, yet not so jagged as would be expected if an individual gas molecule were examined. Forces between two or more molecules or atoms, either attractive or repulsive, are called intermolecular forces . Intermolecular forces are experienced by molecules when they are within physical proximity of one another. These forces are very important for properly modeling molecular systems, as to accurately predict
11562-476: The particles (molecules and atoms) which make up the [gas] system. In statistical mechanics , temperature is the measure of the average kinetic energy stored in a molecule (also known as the thermal energy). The methods of storing this energy are dictated by the degrees of freedom of the molecule itself ( energy modes ). Thermal (kinetic) energy added to a gas or liquid (an endothermic process) produces translational, rotational, and vibrational motion. In contrast,
11685-478: The particles cannot move freely but can only vibrate. As a result, a solid has a stable, definite shape, and a definite volume. Solids can only change their shape by an outside force, as when broken or cut. In crystalline solids , the particles (atoms, molecules, or ions) are packed in a regularly ordered, repeating pattern. There are various different crystal structures , and the same substance can have more than one structure (or solid phase). For example, iron has
11808-409: The particles inside. Once their internal energy is above zero-point energy , meaning their kinetic energy (also known as thermal energy ) is non-zero, the gas particles will begin to move around the container. As the box is further heated (as more energy is added), the individual particles increase their average speed as the system's total internal energy increases. The higher average-speed of all
11931-417: The particles leads to a greater rate at which collisions happen (i.e. greater number of collisions per unit of time), between particles and the container, as well as between the particles themselves. The macro scopic, measurable quantity of pressure, is the direct result of these micro scopic particle collisions with the surface, over which, individual molecules exert a small force, each contributing to
12054-459: The plasma state. Plasma is by far the most abundant of the four fundamental states, as 99% of all ordinary matter in the universe is plasma, as it composes all stars . A state of matter is also characterized by phase transitions . A phase transition indicates a change in structure and can be recognized by an abrupt change in properties. A distinct state of matter can be defined as any set of states distinguished from any other set of states by
12177-475: The pressure is higher than the triple point of the substance. Intermolecular (or interatomic or interionic) forces are still important, but the molecules have enough energy to move relative to each other and the structure is mobile. This means that the shape of a liquid is not definite but is determined by its container. The volume is usually greater than that of the corresponding solid, the best known exception being water , H 2 O. The highest temperature at which
12300-407: The pressure-dependence is neglected (and possibly the temperature-dependence as well) in a particular application, sometimes the gas is said to be a perfect gas , although the exact assumptions may vary depending on the author and/or field of science. For an ideal gas, the ideal gas law applies without restrictions on the specific heat. An ideal gas is a simplified "real gas" with the assumption that
12423-409: The process of sublimation , and gases can likewise change directly into solids through deposition . A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. The volume is definite if the temperature and pressure are constant. When a solid is heated above its melting point , it becomes liquid, given that
12546-400: The region. In contrast, a smaller length scale corresponds to a microscopic or particle point of view. Macroscopically, the gas characteristics measured are either in terms of the gas particles themselves (velocity, pressure, or temperature) or their surroundings (volume). For example, Robert Boyle studied pneumatic chemistry for a small portion of his career. One of his experiments related
12669-428: The same energy and are thus interchangeable. Degenerate matter is supported by the Pauli exclusion principle , which prevents two fermionic particles from occupying the same quantum state. Unlike regular plasma, degenerate plasma expands little when heated, because there are simply no momentum states left. Consequently, degenerate stars collapse into very high densities. More massive degenerate stars are smaller, because
12792-451: The same quantum state, but a pair of fermions can behave as a boson, and multiple such pairs can then enter the same quantum state without restriction. Under extremely high pressure, as in the cores of dead stars, ordinary matter undergoes a transition to a series of exotic states of matter collectively known as degenerate matter , which are supported mainly by quantum mechanical effects. In physics, "degenerate" refers to two states that have
12915-433: The same spin. This gives rise to curious properties, as well as supporting some unusual proposals about the fundamental conditions of the universe itself. Amedeo Avogadro Lorenzo Romano Amedeo Carlo Avogadro, Count of Quaregna and Cerreto ( / ˌ æ v ə ˈ ɡ ɑː d r oʊ / , also US : / ˌ ɑː v -/ , Italian: [ameˈdɛːo avoˈɡaːdro] ; 9 August 1776 – 9 July 1856)
13038-467: The situation: microcanonical ensemble , canonical ensemble , or grand canonical ensemble . Specific combinations of microstates within an ensemble are how we truly define macrostate of the system (temperature, pressure, energy, etc.). In order to do that, we must first count all microstates though use of a partition function . The use of statistical mechanics and the partition function is an important tool throughout all of physical chemistry, because it
13161-513: The spreading out of gases ( entropy ). These events are also described by particle theory . Since it is at the limit of (or beyond) current technology to observe individual gas particles (atoms or molecules), only theoretical calculations give suggestions about how they move, but their motion is different from Brownian motion because Brownian motion involves a smooth drag due to the frictional force of many gas molecules, punctuated by violent collisions of an individual (or several) gas molecule(s) with
13284-404: The surface area of the wall. The symbol used to represent temperature in equations is T with SI units of kelvins . The speed of a gas particle is proportional to its absolute temperature . The volume of the balloon in the video shrinks when the trapped gas particles slow down with the addition of extremely cold nitrogen. The temperature of any physical system is related to the motions of
13407-493: The system. However, in real gases and other real substances, the motions which define the kinetic energy of a system (which collectively determine the temperature), are much more complex than simple linear translation due to the more complex structure of molecules, compared to single atoms which act similarly to point-masses . In real thermodynamic systems, quantum phenomena play a large role in determining thermal motions. The random, thermal motions (kinetic energy) in molecules
13530-434: The total force applied within a specific area. ( Read § Pressure . ) Likewise, the macroscopically measurable quantity of temperature , is a quantification of the overall amount of motion, or kinetic energy that the particles exhibit. ( Read § Temperature . ) In the kinetic theory of gases , kinetic energy is assumed to purely consist of linear translations according to a speed distribution of particles in
13653-678: The unit mole ), 6.022 140 76 × 10 mol , is known as the Avogadro constant . This constant is denoted N A , and is one of the seven defining constants of the SI . Amedeo Avogadro was born in Turin to a noble family of the Kingdom of Sardinia (now part of Italy ) in the year 1776. He graduated in ecclesiastical law at the late age of 20 and began to practice. Soon after, he dedicated himself to physics and mathematics (then called positive philosophy ), and in 1809 started teaching them at
13776-487: The universe may have passed through these states in the Big Bang . A supersolid is a spatially ordered material (that is, a solid or crystal) with superfluid properties. Similar to a superfluid, a supersolid is able to move without friction but retains a rigid shape. Although a supersolid is a solid, it exhibits so many characteristic properties different from other solids that many argue it is another state of matter. In
13899-637: The university in Turin in 1833, where he taught for another twenty years. Little is known about Avogadro's private life, which appears to have been sober and religious. He married Felicita Mazzé and had six children. Avogadro held posts dealing with statistics, meteorology, and weights and measures (he introduced the metric system into Piedmont) and was a member of the Royal Superior Council on Public Instruction. He died on 9 July 1856. In honour of Avogadro's contributions to molecular theory,
14022-407: The upper end of the engine temperature ranges (e.g. combustor sections – 1300 K), the complex fuel particles absorb internal energy by means of rotations and vibrations that cause their specific heats to vary from those of diatomic molecules and noble gases. At more than double that temperature, electronic excitation and dissociation of the gas particles begins to occur causing the pressure to adjust to
14145-411: The use of just a simple calculation to obtain his analytical results. His results were possible because he was studying gases in relatively low pressure situations where they behaved in an "ideal" manner. These ideal relationships apply to safety calculations for a variety of flight conditions on the materials in use. However, the high technology equipment in use today was designed to help us safely explore
14268-575: The word "atom" as the words "atom" and "molecule" were used almost without difference. He believed that there were three kinds of "molecules", including an "elementary molecule" (our "atom"). Also, he gave more attention to the definition of mass , as distinguished from weight . In 1815, he published Mémoire sur les masses relatives des molécules des corps simples, ou densités présumées de leur gaz, et sur la constitution de quelques-uns de leur composés, pour servir de suite à l'Essai sur le même sujet, publié dans le Journal de Physique, juillet 1811 ("Note on
14391-532: The year 2000. Unlike plasma, which flows like a gas, interactions within QGP are strong and it flows like a liquid. At high densities but relatively low temperatures, quarks are theorized to form a quark liquid whose nature is presently unknown. It forms a distinct color-flavor locked (CFL) phase at even higher densities. This phase is superconductive for color charge. These phases may occur in neutron stars but they are presently theoretical. Color-glass condensate
14514-441: Was active in the revolutionary movement of March 1821. As a result, he lost his chair in 1823 (or, as the university officially declared, it was "very glad to allow this interesting scientist to take a rest from heavy teaching duties, in order to be able to give better attention to his researches"). Eventually, King Charles Albert granted a Constitution ( Statuto Albertino ) in 1848. Well before this, Avogadro had been recalled to
14637-429: Was an Italian scientist , most noted for his contribution to molecular theory now known as Avogadro's law , which states that equal volumes of gases under the same conditions of temperature and pressure will contain equal numbers of molecules. In tribute to him, the ratio of the number of elementary entities ( atoms , molecules , ions or other particles) in a substance to its amount of substance (the latter having
14760-518: Was finally resolved by Stanislao Cannizzaro , as announced at Karlsruhe Congress in 1860, four years after Avogadro's death. He explained that these exceptions were due to molecular dissociations at certain temperatures, and that Avogadro's law determined not only molecular masses but atomic masses as well. In 1911, a meeting in Turin commemorated the hundredth anniversary of the publication of Avogadro's classic 1811 paper. King Victor Emmanuel III attended, and Avogadro's great contribution to chemistry
14883-541: Was first used by the early 17th-century Flemish chemist Jan Baptist van Helmont . He identified carbon dioxide , the first known gas other than air. Van Helmont's word appears to have been simply a phonetic transcription of the Ancient Greek word χάος ' chaos ' – the g in Dutch being pronounced like ch in " loch " (voiceless velar fricative, / x / ) – in which case Van Helmont simply
15006-497: Was following the established alchemical usage first attested in the works of Paracelsus . According to Paracelsus's terminology, chaos meant something like ' ultra-rarefied water ' . An alternative story is that Van Helmont's term was derived from " gahst (or geist ), which signifies a ghost or spirit". That story is given no credence by the editors of the Oxford English Dictionary . In contrast,
15129-611: Was not immediately accepted. André-Marie Ampère proposed a very similar theory three years later (in his Sur la détermination des proportions dans lesquelles les corps se combinent d'après le nombre et la disposition respective des molécules dont leurs particules intégrantes sont composées ; "On the Determination of Proportions in which Bodies Combine According to the Number and the Respective Disposition of
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