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Gas phase particles (atoms, molecules, or ions) move around freely

A gas is one of the states of matter, consisting of a collection of particles (molecules, atoms, ions, electrons, etc.) without a definite shape or volume that are in more or less random motion. Look up gas in Wiktionary, the free dictionary. ... Image File history File links Gas_particle_movement. ... Image File history File links Gas_particle_movement. ... Properties For alternative meanings see atom (disambiguation). ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ... This article is about the electrically charged particle. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ... For other uses, see Atom (disambiguation). ... This article is about the electrically charged particle. ... For other uses, see Electron (disambiguation). ...

Due to the electronic nature of the aforementioned particles, a "force field" is present throughout the space around them. Interactions between these "force fields" from one particle to the next give rise to the name intermolecular forces. Dependent on distance, these intermolecular forces influence the motion of these particles and hence their thermodynamic properties. It must be noted that at the temperatures and pressures characteristic of many applications, these particles are normally greatly separated. This separation corresponds to a very weak attractive force. As a result, for many applications, this intermolecular force becomes negligible. Originally a term coined by Michael Faraday to provide an intuitive paradigm, but theoretical construct (in the Kuhnian sense), for the behavior of electromagnetic fields, the term force field refers to the lines of force one object (the source object) exerts on another object or a collection of other objects. ... In physics, chemistry, and biology, intermolecular forces are forces that act between stable molecules or between functional groups of macromolecules. ... Here is a partial list of thermodynamic properties of fluids: temperature [K] density [kg/m3] specific heat at constant pressure [J/kgÂ·K] specific heat at constant volume [J/kgÂ·K] dynamic viscosity [N/mÂ²s] kinematic viscosity [mÂ²/s] thermal conductivity [W/mÂ·K] thermal diffusivity [mÂ²/s] volumetric...

A gas also exhibits the following characteristics:

• Relatively low density and viscosity compared to the solid and liquid states of matter.
• Will expand and contract greatly with changes in temperature or pressure, thus the term "compressible".
• Will diffuse readily, spreading apart in order to homogeneously distribute itself throughout any container.

Macroscopic

When analyzing a system, it is typical to specify a length scale. A larger length scale may correspond to a macroscopic view of the system, while a smaller length scale corresponds to a microscopic view. In physics, length scale is a particular length or distance determined with the precision of one order (or a few orders) of magnitude. ... Macroscopic is commonly used to describe physical objects that are measurable and observable by the naked eye. ... A microscope (Greek: micron = small and scopos = aim) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. ...

On a macroscopic scale, the quantities measured are in terms of the large scale effects that a gas has on a system or its surroundings such as its velocity, pressure, or temperature. Mathematical equations, such as the Extended hydrodynamic equations, Navier-Stokes equations and the Euler equations have been developed to attempt to model the relations of the pressure, density, temperature, and velocity of a moving gas. The Navier-Stokes equations, named after Claude-Louis Navier and George Gabriel Stokes, are a set of equations which describe the motion of fluid substances such as liquids and gases. ... In fluid dynamics, the Euler equations govern the compressible, Inviscid flow. ...

Pressure

Main article: Pressure

The pressure exerted by a gas uniformly across the surface of a container can be described by simple kinetic theory. The particles of a gas are constantly moving in random directions and frequently collide with the walls of the container and/or each other. These particles all exhibit the physical properties of mass, momentum, and energy, which all must be conserved. In classical mechanics, Momentum, by definition, is the product of mass and velocity. Kinetic energy is one half the mass multiplied by the square of the velocity. This article is about pressure in the physical sciences. ... Kinetic theory or kinetic theory of gases attempts to explain macroscopic properties of gases, such as pressure, temperature, or volume, by considering their molecular composition and motion. ... A physical property is any aspect of an object or substance that can be measured or perceived without changing its identity. ... For other uses, see Mass (disambiguation). ... This article is about momentum in physics. ... In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves. ... Classical mechanics (commonly confused with Newtonian mechanics, which is a subfield thereof) is used for describing the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies. ... The cars of a roller coaster reach their maximum kinetic energy when at the bottom of their path. ...

The sum of all the normal components of force exerted by the particles impacting the walls of the container divided by the area of the wall is defined to be the pressure. The pressure can then be said to be the average linear momentum of these moving particles. A common misconception is that the collisions of the molecules with each other is essential to explain gas pressure, but in fact their random velocities are sufficient to define this quantity. Illustration of tangential and normal components of a vector to a surface. ... In physics, momentum is a physical quantity related to the velocity and mass of an object. ...

Temperature

The temperature of any physical system is the result of the motions of the molecules and atoms which make up the system. In statistical mechanics, temperature is the measure of the average kinetic energy stored in a particle. The methods of storing this energy are dictated by the degrees of freedom of the particle itself (energy modes). These particles have a range of different velocities, and the velocity of any single particle constantly changes due to collisions with other particles. The range in speed is usually described by the Maxwell-Boltzmann distribution. Thermodynamic temperature is the absolute measure of temperature and is one of the principal parameters of thermodynamics. ... A physical system is a system that is comprised of matter and energy. ... Statistical mechanics is the application of probability theory, which includes mathematical tools for dealing with large populations, to the field of mechanics, which is concerned with the motion of particles or objects when subjected to a force. ... Degrees of freedom is a general term used in explaining dependence on parameters, and implying the possibility of counting the number of those parameters. ... A quantum mechanical system can only be in certain states, so that only certain energy levels are possible. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...

Specific Volume

Main article: Specific volume

When performing a thermodynamic analysis, it is typical to speak of intensive and extensive properties. Properties which depend on the amount of gas 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 volume occupied by a unit of mass of a material, meaning we have divided through by the mass in order to obtain a quantity in terms of, for example,$textstyle frac{m^3}{kg}$. Notice that the difference between volume and specific volume differ in that the specific quantity is mass independent. Specific volume is the volume of a unit of mass of a material. ... In physics and chemistry an intensive property (also called a bulk property) of a system is a physical property of the system that does not depend on the system size or the amount of material in the system. ...

Density

Main article: Density

Because the molecules are free to move about in a gas, the mass of the gas is normally characterized by its density. Density is the mass per volume of a substance or simply, the inverse of specific volume. For gases, the density can vary over a wide range because the molecules are free to move. Macroscopically, density is a state variable of a gas and the change in density during any process is governed by the laws of thermodynamics. Given that there are many particles in completely random motion, for a static gas, the density is the same throughout the entire container. Density is therefore a scalar quantity; it is a simple physical quantity that has a magnitude but no direction associated with it. It can be shown by kinetic theory that the density is proportional to the size of the container in which a fixed mass of gas is confined. For other uses, see Density (disambiguation). ... A state variable is any variable which represents the state of an object. ... Fluid statics (also called hydrostatics) is the science of fluids at rest, and is a sub-field within fluid mechanics. ... See scalar for an account of the broader concept also used in mathematics and computer science. ...

Microscopic

Main article: Microscopic

On the microscopic scale, the quantities measured are at the molecular level. Different theories and mathematical models have been created to describe molecular or particle motion. A few of the gas-related models are listed below. A microscope (Greek: micron = small and scopos = aim) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. ...

Kinetic theory

Main article: Kinetic theory

Kinetic theory attempts to explain macroscopic properties of gases by considering their molecular composition and motion. Kinetic theory or kinetic theory of gases attempts to explain macroscopic properties of gases, such as pressure, temperature, or volume, by considering their molecular composition and motion. ...

Brownian motion

Main article: Brownian motion

Brownian motion is the mathematical model used to describe the random movement of particles suspended in a fluid often called particle theory. Three different views of Brownian motion, with 32 steps, 256 steps, and 2048 steps denoted by progressively lighter colors. ... Thousands of particles explode from the collision point of two relativistic (100 GeV per nucleon) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ...

Since it is at the limit of (or beyond) current technology to observe individual gas particles (atoms or molecules), only theoretical calculations give suggestions as to how they move, but their motion is different from Brownian Motion. The reason is that 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 the particle. The particle (generally consisting of millions or billions of atoms) thus moves in a jagged course, yet not so jagged as we would expect to find if we could examine an individual gas molecule.

Intermolecular forces

Main article: Van der Waals force See Also: Intermolecular force In chemistry, the term van der Waals force originally referred to all forms of intermolecular forces; however, in modern usage it tends to refer to intermolecular forces that deal with forces due to the polarization of molecules. ... In physics, chemistry, and biology, intermolecular forces are forces that act between stable molecules or between functional groups of macromolecules. ...

As discussed earlier, momentary attractions (or repulsions) between particles have an effect on gas dynamics. In physical chemistry, the name given to these "intermolecular forces" is the "Van der Waals force". A gas-dynamic control system is one where the path of an object in flight is controlled by either the generation or redirection of gas flow out of an orifice rather than with the traditional movable control surfaces. ... Physical chemistry is the application of physics to macroscopic, microscopic, atomic, subatomic, and particulate phenomena in chemical systems[1]within the field of chemistry traditionally using the principles, practices and concepts of thermodynamics, quantum chemistry, statistical mechanics and kinetics. ...

Simplified models

Main article: Equation of state

An equation of state (for gases) is a mathematical model used to roughly describe or predict the state of a gas. At present, there is no single equation of state that accurately predicts the properties of all gases under all conditions. Therefore, a number of much more accurate equations of state have been developed for gases under a given set of assumptions. The "gas models" that are most widely discussed are "Real Gas", "Ideal Gas" and "Perfect Gas". Each of these models have their own set of assumptions to, basically, make our lives easier when we want to analyze a given thermodynamic system. In physics and thermodynamics, an equation of state is a relation between state variables. ...

Real gas

Main article: Real gas

Real gas effects refers to an assumption base where the following are taken into account: An ideal gas (also called a perfect gas) is a hypothetical fluid consisting of particles that are identical to each other, occupy negligible volume and undergo perfect elastic collisions with each other, with no intermolecular forces and no intramolecular storage of energy, as opposed to a real gas, a gas...

For most applications, such a detailed analysis is excessive. An example where "Real Gas effects" would have a significant impact would be on the Space Shuttle re-entry where extremely high temperatures and pressures are present. Fluid Dynamics Compressibility (physics) is a measure of the relative volume change of fluid or solid as a response to a pressure (or mean stress) change: . For a gas the magnitude of the compressibility depends strongly on whether the process is adiabatic or isothermal, while this difference is small in... To meet Wikipedias quality standards, this article or section may require cleanup. ... Non-equilibrium thermodynamics is a branch of thermodynamics concerned with studying time-dependent thermodynamic systems, irreversible transformations and open systems. ... Dissociation in chemistry and biochemistry is a general process in which complexes, molecules, or salts separate or split into smaller molecules, ions, or radicals, usually in a reversible manner. ... The IUPAC Compendium of Chemical Terminology defines elementary reaction as A reaction for which no reaction intermediates have been detected or need to be postulated in order to describe the chemical reaction on a molecular scale. ... This article is about the space vehicle. ... â€œReentryâ€ redirects here. ...

Ideal gas

An "ideal gas" is a simplified "real gas" with the following assumptions:

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 a combustion chamber of a jet engine. It may also be useful to keep the elementary reactions and chemical dissociations for calculating emissions. Fluid Dynamics Compressibility (physics) is a measure of the relative volume change of fluid or solid as a response to a pressure (or mean stress) change: . For a gas the magnitude of the compressibility depends strongly on whether the process is adiabatic or isothermal, while this difference is small in... Fluid Dynamics Compressibility (physics) is a measure of the relative volume change of fluid or solid as a response to a pressure (or mean stress) change: . For a gas the magnitude of the compressibility depends strongly on whether the process is adiabatic or isothermal, while this difference is small in... Isotherms of an ideal gas The ideal gas law is the equation of state of a hypothetical ideal gas, first stated by BenoÃ®t Paul Ã‰mile Clapeyron in 1834. ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ... Automobile exhaust Exhaust gas is flue gas which occurs as a result of the combustion of fuels such as natural gas, gasoline/petrol, diesel, fuel oil or coal. ...

Perfect gas

Main article: Perfect gas

By definition, A perfect gas is one in which intermolecular forces are neglected. So, along with the assumptions of an Ideal Gas, the following assumptions are added: An ideal gas (also called a perfect gas) is a hypothetical fluid consisting of particles that are identical to each other, occupy negligible volume and undergo perfect elastic collisions with each other, with no intermolecular forces and no intramolecular storage of energy, as opposed to a real gas, a gas...

• Neglected intermolecular forces

By neglecting these forces, the equation of state for a perfect gas can be simply derived from kinetic theory or statistical mechanics.

This type of assumption is useful for making calculations very simple and easy to do. With this assumption we can apply the Ideal gas law without restriction and neglect many complications that may arise from the Van der Waals forces.

Along with the definition of a perfect gas, there are also two more simplifications that can be made although various textbooks either omit or combine the following simplifications into a general "perfect gas" definition. For sake of clarity, these simplifications are defined separately.

Thermally perfect

Main article: Thermally perfect gas

e = e(T) h = h(T) de = CvdT dh = CpdT In thermodynamics, a thermodynamic system is said to be in thermodynamic equilibrium when it is in thermal equilibrium, mechanical equilibrium, and chemical equilibrium. ... In thermodynamics, the internal energy of a thermodynamic system, or a body with well-defined boundaries, denoted by U, or sometimes E, is the total of the kinetic energy due to the motion of molecules (translational, rotational, vibrational) and the potential energy associated with the vibrational and electric energy of... t In thermodynamics and molecular chemistry, the enthalpy or heat content (denoted as H or Î”H, or rarely as Ï‡) is a quotient or description of thermodynamic potential of a system, which can be used to calculate the useful work obtainable from a closed thermodynamic system under constant pressure. ... The specific heat capacity (symbol c or s, also called specific heat) of a substance is defined as heat capacity per unit mass. ...

This type of approximation is useful for modeling, for example, an axial compressor where temperature fluctuations are usually not large enough to cause any significant deviations from the Thermally perfect gas model. Heat capacity is still allowed to vary, though only with temperature and molecules are not permitted to dissociate. This article does not cite any references or sources. ...

Calorically perfect

Main article: Calorically perfect gas

Finally, the most restricted gas model is one where all the above assumptions apply and we also apply:

• Constant Specific Heats

e = CvT h = CpT

Although this may be the most restrictive model, it still may be accurate enough to make reasonable calculations. For example, if a model of one compression stage of the axial compressor mentioned in the previous example was made (one with variable Cp, and one with constant Cp) to compare the two simplifications, the deviation may be found at a small enough order of magnitude that other factors that come into play in this compression would have a greater impact on the final result than whether or not Cp was held constant. (compressor tip-clearance, boundary layer/frictional losses, manufacturing impurities, etc.)

Historical Synthesis

Main article: Boyle's Law

Boyle's Law was perhaps the first expression of an equation of state. In 1662 Robert Boyle, an Irishman, performed a series of experiments employing a J-shaped glass tube, which was sealed on one end. Mercury was added to the tube, trapping a fixed quantity of air in the short, sealed end of the tube. Then the volume of gas was carefully measured as additional mercury was added to the tube. The pressure of the gas could be determined by the difference between the mercury level in the short end of the tube and that in the long, open end. Through these experiments, Boyle noted that the gas volume varied inversely with the pressure. In mathematical form, this can be stated as: pV = constant. Boyles law (sometimes referred to as the Boyle-Mariotte law) is one of the gas laws and basis of derivation for the ideal gas law, which describes the relationship between the product pressure and volume within a closed system as constant when temperature remains at a fixed measure; both...

This law is used widely to describe different thermodynamic processes by adjusting the equation to read pVn = constant and then varying the n through different values such as the specific heat ratio, γ. A thermodynamic process may be defined as the energetic evolution of a thermodynamic system proceeding from an initial state to a final state. ... The heat capacity ratio is simply the ratio of the heat capacity at constant pressure to that at constant volume It should be noted that chemical engineers and many others commonly refer to the heat capacity ratio as rather than . ...

Main article: Charles Law

In 1787 the French physicist Jacques Charles found that oxygen, nitrogen, hydrogen, carbon dioxide, and air expand to the same extent over the same 80 kelvin interval. The Law of Charles and Gay-Lussac (frequently called simply Charles Law) is one of the gas laws, and relates the volume and temperature of an ideal gas held at a constant pressure. ... Jacques Alexandre CÃ©sar Charles, 1820 First flight by Prof. ...

Main article: Gay-Lussac's Law

In 1802, Joseph Louis Gay-Lussac published results of similar experiments, indicating a linear relationship between volume and temperature: V1 / T1 = V2 / T2 Gay-Lussacs law is one of two laws named after the French chemist Joseph Louis Gay-Lussac, which relate to the properties of gases and are known by the same name. ... Joseph Louis Gay-Lussac. ...

Main article: Dalton's law

In 1801 John Dalton published the Law of Partial Pressures: The pressure of a mixture of gases is equal to the sum of the pressures of all of the constituent gases alone. Mathematically, this can be represented for n species as: Pressuretotal = Pressure1 + Pressure2 + ... + Pressuren In chemistry and physics, Daltons law (also called Daltons law of partial pressures) states that the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component in a gas mixture. ... John Dalton John Dalton (September 6, 1766 â€“ July 27, 1844) was an English chemist and physicist, born at Eaglesfield, near Cockermouth in Cumberland. ...

Special Topics

Compressibility

The compressibility factor (Z) is used to alter the ideal gas equation to account for the real gas behavior. It is sometimes referred to as a "fudge-factor" to make the ideal gas law more accurate for the application. Usually this Z value is very close to unity. Fluid Dynamics Compressibility (physics) is a measure of the relative volume change of fluid or solid as a response to a pressure (or mean stress) change: . For a gas the magnitude of the compressibility depends strongly on whether the process is adiabatic or isothermal, while this difference is small in...

Reynolds Number

Main article: Reynolds number

In fluid mechanics, the Reynolds number is the ratio of inertial forces (vsρ) to viscous forces (μ/L). It is one of the most important dimensionless numbers in fluid dynamics and is used, usually along with other dimensionless numbers, to provide a criterion for determining dynamic similitude. In fluid mechanics, the Reynolds number may be described as the ratio of inertial forces (vsÏ) to viscous forces (Î¼/L) and, consequently, it quantifies the relative importance of these two types of forces for given flow conditions. ...

Viscosity

Main article: Viscosity

As we saw earlier: Pressure acts perpendicular (normal) to the wall. The tangential (shear) component of the force that is left over is related to the viscosity of the gas. As an object moves through a gas, viscous effects become more prevalent. For other uses, see Viscosity (disambiguation). ...

Turbulence

Main article: Turbulence

In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic, stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time. In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic, stochastic property changes. ...

Boundary Layer

Main article: Boundary layer

Particles will, in effect, "stick" to the surface of an object moving through it. This layer of particles is called the boundary layer. At the surface of the object, it is essentially static due to the friction of the surface. The object, with its boundary layer is effectively the new shape of the object that the rest of the molecules "see" as the object approaches. This boundary layer can separate from the surface, essentially creating a new surface and completely changing the flow path. The classical example of this is a stalling airfoil. In physics and fluid mechanics, a boundary layer is that layer of fluid in the immediate vicinity of a bounding surface. ... In aerodynamics, a stall is a condition in which an excessive angle of attack causes loss of lift due to disruption of airflow. ...

Maximum Entropy Principle

As the total number of degrees of freedom approaches infinity, the system will be found in the macrostate that corresponds to the highest multiplicity. The principle of maximum entropy is a method for analyzing the available information in order to determine a unique epistemic probability distribution. ... In thermodynamics, a microstate describes a specific detailed microscopic configuration of a system. ... In mathematics, the multiplicity of a member of a multiset is how many memberships in the multiset it has. ...

Thermodynamic Equilibrium

Equilibrium thermodynamics applies if the energy change within a system occurs on a timescale large enough for a sufficient number of molecular collisions to occur so that the energy transfer between molecules and between energy modes to allow the new energy value to be distributed in equilibrium among the molecules. (For typical systems, this is on the order of a few nanoseconds) In thermodynamics, a thermodynamic system is said to be in thermodynamic equilibrium when it is in thermal equilibrium, mechanical equilibrium, and chemical equilibrium. ...

Look up Gas in
Wiktionary, the free dictionary.

Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 151 languages. ...

References

• John D. Anderson. Modern Compressible Flow: Third Edition New York, NY : McGraw-Hill, 2004. ISBN 007-124136-1
• Philip Hill and Carl Peterson. Mechanics and Thermodynamics of Propulsion: Second Edition Addison-Wesley, 1992. ISBN 0-201-14659-2
• John D. Anderson. Fundamentals of Aerodynamics: Fourth Edition New York, NY : McGraw-Hill, 2007. ISBN-13: 978-0-07-295046-5 ISBN-10: 0-07-295046-3
• National Aeronautics and Space Administration (NASA). Animated Gas Lab. Accessed February, 2008.
• Georgia State University. HyperPhysics. Accessed February, 2008.
• Antony Lewis WordWeb. Accessed February, 2008.
• Northwestern Michigan College The Gaseous State. Accessed February, 2008.
In the physical sciences, a state of matter is one of the many ways that matter can interact with itself to form a macroscopic, homogenous phase. ... This box:      For other uses, see Solid (disambiguation). ... For other uses, see Liquid (disambiguation). ... For other uses, see Plasma. ... A Colloid or colloidal dispersion is a type of homogeneous mixture. ... A supercritical fluid is any substance at a temperature and pressure above its thermodynamic critical point. ... Helium II will creep along surfaces in order to find its own level - after a short while, the levels in the two containers will equalize. ... Phase diagram for 4He A supersolid is a spatially ordered superfluid. ... Degenerate matter is matter which has sufficiently high density that the dominant contribution to its pressure arises from the Pauli exclusion principle. ... A QGP is formed at the collision point of two relativistically accelerated gold ions in the center of the STAR detector at the relativistic heavy ion collider at the Brookhaven national laboratory. ... A fermionic condensate is a superfluid phase formed by fermionic particles at low temperatures. ... A Boseâ€“Einstein condensate (BEC) is a state of matter formed by a system of bosons confined in an external potential and cooled to temperatures very near to absolute zero (0 kelvin or âˆ’273. ... This article is considered orphaned, since there are very few or no other articles that link to this one. ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ... Italic text This article is about the boiling point of liquids. ... In physics, the triple point of a substance is the temperature and pressure at which three phases (gas, liquid, and solid) of that substance may coexist in thermodynamic equilibrium. ... In physical chemistry, thermodynamics, chemistry and condensed matter physics, a critical point, also called a critical state, specifies the conditions (temperature, pressure) at which the liquid state of the matter ceases to exist. ... In physics and thermodynamics, an equation of state is a relation between state variables. ... A cooling curve of naphthalene from liquid to solid. ... This is a list of the different states of matter including the more exotic ones (see phases of matter). ...

Results from FactBites:

 Gas - Wikipedia, the free encyclopedia (679 words) A gas is one of the four major phases of matter (after solid and liquid, and followed by plasma, that subsequently appear as a solid material is subjected to increasingly higher temperatures. The thermodynamic state of a gas is characterized by its volume, its temperature, which is determined by the average velocity or kinetic energy of the molecules, and its pressure, which measures the average force exerted by the molecules colliding against a surface. The word "gas" was apparently proposed by the 17th century chemist Jan Baptist van Helmont, as a phonetic spelling of his Dutch pronunciation of the Greek word "chaos".
 First World War.com - Weapons of War - Poison Gas (1737 words) The Germans' use of chlorine gas provoked immediate widespread condemnation, and certainly damaged German relations with the neutral powers, including the U.S. The gas attacks were placed to rapid propaganda use by the British although they planned to respond in kind. Raising Special Gas Companies in the wake of the Germans' April attack (of approximately 1,400 men) operating under the command of Lieutenant-Colonel Charles Foulkes, instructions were given to prepare for a gas attack at Loos in September 1915. Gas never turned out to be the weapon that turned the tide of the war, as was often predicted.
More results at FactBites »

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