Gas

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Posted by kaori 02/25/2009 @ 15:25

Tags : gas, energy and water, business

News headlines
Estimate Places Natural Gas Reserves 35% Higher - New York Times
By JAD MOUAWAD Thanks to new drilling technologies that are unlocking substantial amounts of natural gas from shale rocks, the nation's estimated gas reserves have surged by 35 percent, according to a study due for release on Thursday....
Local gas prices up 10 cents over past week - The Columbian
Retail gas prices continued to rise this week in Vancouver, where motorists spent an average of $2.78 a gallon for regular unleaded, according to AAA Oregon/Idaho. That's up from $2.68 last week. AAA said the increase reflects the rising commodity...
Rising gas prices hit drivers nationwide - CNNMoney.com
More NEW YORK (cnnmoney.com) -- Gas prices have risen for 50 days in a row and the pain at the pump is taking a toll on household budgets across the nation. Nationwide, gas prices now average $2.679, motorist group AAA said Wednesday....
Hungary's MOL to Build Storage for Natural Gas - Wall Street Journal
By PAUL HANNON LONDON -- The European Bank for Reconstruction and Development said it will lend €200 million ($277 million) to Hungarian energy company MOL Nyrt. for the construction of a gas storage facility that would help the country bridge future...
Gary gas station owner laments fatal robbery - Chicago Tribune
By Cara Anthony | Tribune reporter Randy Singh says he trains employees at his Gary gas mini-mart to give up the cash without a fight if robbed. But his nephew, a native of India who had worked at the business for about a year, was fatally shot Sunday...
Ecopetrol, Chevron Ship 300M Cf/D Of Gas To Venezuela - Wall Street Journal
(CVX) currently export 300 million cubic feet of gas to Venezuela through the pipeline linking the Ballena gas field to Maracaibo, Ecopetrol's Chief Executive, Javier Gutierrez, said Wednesday. The Venezuelan state-owned oil company Petroleos de...
India May Lose $831 Million on Reliance Gas Verdict, Times Says - Bloomberg
By Rakteem Katakey June 18 (Bloomberg) -- India may lose 40 billion rupees ($831 million) in royalty payments from Reliance Industries Ltd. if it sells natural gas at lower prices to Reliance Natural Resources Ltd., the Economic Times reported,...
RPT-E.ON aims to close Italian gas grid sale by yr-end - sources - Reuters
DE) aims to wrap up the sale of its gas distribution grid in Italy by the end of the year and potential investors have already been sounded out, two financial sources close to the matter said on Wednesday. While investors were being talked to,...
Colombia: Oil, Gas Reserves Have Increased Substantially - Wall Street Journal
BOGOTA (Dow Jones)--Colombian oil and gas reserves have increased "substantially," Armando Zamora, head of Colombia's oil and gas licensing agency, said Wednesday. He said the increased reserves are from existing fields, not new discoveries....
LETTERS: Albany, gas prices and more - Newsday
If you are hired for a job but then do the opposite of what the boss hired you to do, should you be fired? At the least, you should be reprimanded and called before the boss to explain your actions - and replaced if the matter is not resolved....

Gas chamber

Roof of Majdanek gas chamber showing vents through which Zyklon B was inserted

A gas chamber is an apparatus for killing, consisting of a sealed chamber into which a poisonous or asphyxiant gas is introduced. The most commonly used poisonous agent is hydrogen cyanide; carbon dioxide and carbon monoxide have also been used. Gas chambers were used as a method of execution for condemned prisoners in the United States beginning in the 1920s. During the Holocaust, large-scale gas chambers designed for mass killing were used by Nazi Germany as part of their genocide program. The use of gas chambers has also been reported in North Korea.

Gas chambers have also been used for animal euthanasia, using carbon monoxide as the lethal agent. Sometimes a box filled with anaesthetic gas is used to anaesthetize small animals for surgery or euthanasia.

Gas chambers were used in the Third Reich as part of the "public euthanasia program" aimed at eliminating physically and intellectually disabled people and political undesirables in the 1930s and 1940s. At that time, the preferred gas was carbon monoxide, often provided by the exhaust gas of cars, trucks or army tanks.

During the Holocaust, gas chambers were designed to accept large groups as part of the Nazi policy of genocide against the Jews. Nazis also targeted the Romani people, homosexuals, physically and mentally disabled, and intellectuals. In early 1940, the use of hydrogen cyanide produced as Zyklon B was tested on 250 Roma children from Brno at the Buchenwald concentration camp. On September 3, 1941, 600 Soviet POWs were gassed with Zyklon B at Auschwitz camp I; this was the first experiment with the gas at Auschwitz.

Carbon monoxide was also used in large purpose-built gas chambers. The gas was provided by internal combustion engines (detailed in the Gerstein Report).

Gas chambers in vans, concentration camps, and extermination camps were used to kill several million people between 1941 and 1945. Some stationary gas chambers could kill 2,500 people at once. Rudolf Höß, Commandant of the Auschwitz concentration camp, attested to the use of gas chambers in the Holocaust.

The gas chambers were dismantled or destroyed when Soviet troops got close, except at Dachau, Sachsenhausen, and Majdanek. The gas chamber at Auschwitz I was reconstructed after the war as a memorial, but without a door in its doorway and without the wall that originally separated the gas chamber from a washroom. The door that had been added when the gas chamber was converted into an air raid shelter was left intact.

Execution by exaust gas was performed in specially modified vans, known as gaswagen (variously translated as "gas wagon", "gas van", or "gas car").

Gas chambers have been used for capital punishment in the United States to execute criminals, especially convicted murderers. The first person to be executed in the United States by gas chamber was Gee Jon, on February 8, 1924 in Nevada. In 1957, Burton Abbott was executed as the governor of California, Goodwin J. Knight, was on the telephone to stay the execution. Since the restoration of the death penalty in the United States in 1976, only eleven executions by gas chamber have been conducted. By the 1980s, reports of suffering during gas chamber executions had led to controversy over the use of this method.

During the April 6, 1992 execution of Donald Harding in Arizona, it took 11 minutes for death to occur. The prison warden stated that he would quit if required to conduct another gas chamber execution. Following Harding's execution, Arizona voted that all persons condemned after November 1992 would be executed by lethal injection.

Following the execution of Robert Alton Harris, a federal court declared that "execution by lethal gas under the California protocol is unconstitutionally cruel and unusual." By the late 20th century, most states had switched to methods considered to be more humane, such as lethal injection. California's gas chamber at San Quentin State Prison was converted to an execution chamber for lethal injection.

As of 2006, the last person to be executed in the gas chamber was German national Walter LaGrand, sentenced to death before 1992, who was executed in Arizona on March 3, 1999. The 9th U.S. Circuit Court of Appeals had ruled that he could not be executed by gas chamber, but the decision was overturned by the U.S. Supreme Court. The gas chamber was formerly used in Colorado, Mississippi, Nevada, New Mexico, North Carolina, Oregon, Wyoming and California. (Lethal gas as the execution method for the State of California was declared unconstitutional by a federal judge in 1994.) Three states, Arizona, Maryland, and Missouri, retain the gas chamber as a secondary method of execution for inmates sentenced to death or having committed capital crimes before certain dates, though they have lethal injection as the primary method.

The gas is visible to the condemned, and he/she is advised to take several deep breaths to speed unconsciousness in order to prevent unnecessary suffering. Accordingly, execution by gas chamber is especially unpleasant for the witnesses to the execution due to the physical responses exhibited by the condemned during the process of dying. These responses can be violent, and can include convulsions and excessive drooling. It is unknown whether or not the condemned actually experiences pain during the process. However, a Federal judge in California ordered that a specific gas chamber execution be filmed for her subsequent review. She wanted to determine whether the gas chamber fit the description of "cruel and unusual punishment". After witnessing the film, her ruling paved the way for the gas chamber to be removed from use in California.

Following the execution, the chamber is purged of the gas through special scrubbers, and must be neutralized with anhydrous ammonia (NH3) before it can be opened. Guards wearing oxygen masks remove the body from the chamber. Finally, the prison doctor examines the individual in order to officially declare that he or she is dead and release the body to the next of kin.

The anhydrous ammonia used to clean the chamber afterwards, and the contaminated acid that must be drained and disposed of, are both very poisonous.

Nitrogen gas or oxygen-depleted air has been considered for human execution, as it can induce Nitrogen asphyxiation. It has not been used to date.

In his book, Le Crime de Napoléon, French historian Claude Ribbe has claimed that in the early 19th century, Napoleon used poison gas to put down slave rebellions in Haiti and Guadeloupe. Based on accounts left by French officers, he alleges that enclosed spaces including the holds of ships were used as makeshift gas chambers where sulfur dioxide gas (probably generated by burning sulfur) was used to execute up to 100,000 rebellious slaves. These claims remain controversial.

The former gas chamber in New Mexico State Penitentiary, Used only once in 1961, subsequently replaced by lethal injection.

The former gas chamber in San Quentin State Prison, now an execution chamber for lethal injection.

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Gas

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

In physics, a gas is a state 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.

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 term intermolecular forces. Dependent on distance, these intermolecular forces influence the motion of these particles and hence their thermodynamic properties. 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.

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.

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 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.

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.

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.

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 the volume has been divided through by the mass in order to obtain a quantity in terms of, for example,. Notice that the difference between volume and specific volume differ in that the specific quantity is mass independent.

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.

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.

Kinetic theory attempts to explain macroscopic properties of gases by considering their molecular composition and motion.

Brownian motion is the mathematical model used to describe the random movement of particles suspended in a fluid often called 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 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 would be expected if an individual gas molecule was examined.

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 van der Waals force.

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 facilitate the analysis of a given thermodynamic system.

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.

An "ideal gas" is a simplified "real gas" with the assumption that the compressibility factor Z is set to 1. So the state variables 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 a combustion chamber of a jet engine. It may also be useful to keep the elementary reactions and chemical dissociations for calculating emissions.

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, the Ideal gas law can be applied without restriction and many complications that may arise from the Van der Waals forces can be neglected.

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.

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.

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.

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.

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 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.

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.

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.

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.

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.

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 word "gas" was invented by Jan Baptist van Helmont, perhaps as a Dutch pronunciation re-spelling of "chaos".

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Poison gas in World War I

British infantry advancing through gas at Loos, 25 September 1915.

The use of poison gas in World War I was a major military innovation. The gases ranged from disabling chemicals, such as tear gas and the severe mustard gas, to lethal agents like phosgene and chlorine. This chemical warfare was a major component of the first global war and first total war of the 20th century. The killing capacity of gas, however, was limited — only 4% of combat deaths were due to gas. Because it was possible to develop effective countermeasures against gas attacks, it was unlike most other weapons of the period. In the later stages of the war, as the use of gas increased, its overall effectiveness diminished. This widespread use of these agents of chemical warfare, and wartime advances in the composition of high explosives, gave rise to an occasionally expressed view of World War I as "the chemists' war".

The early uses of chemicals as weapons were as a tear-inducing irritant (lachrymatory), rather than fatal or disabling poisons. During the first World War, the French were the first to employ gas, using 26 mm grenades filled with tear gas (ethyl bromoacetate) in August, 1914. The small quantities of tear gas delivered, roughly 19 cc per cartridge, were not even detected by the Germans. The stocks were rapidly consumed and by November a new order was placed by the French military. As bromine was scarce among the Entente allies, the active ingredient was changed to chloroacetone.

In October 1914, German troops fired fragmentation shells filled with a chemical irritant against British positions at Neuve Chapelle, though the concentration achieved was so small that it was barely noticed. None of the combatants considered the use of tear gas to be in conflict with the Hague Treaty of 1899, which prohibited the launching of projectiles containing asphyxiating or poisonous gas.

Germany was the first to make large scale use of gas as a weapon when on 3 January 1915, 18,000 artillery shells containing liquid xylyl bromide tear gas were fired on Russian positions on the Rawka River, west of Warsaw during the Battle of Bolimov. However, instead of vaporizing, the chemical froze, completely failing to have the desired effect.

The first killing agent employed by the German military was chlorine. German chemical companies BASF, Hoechst and Bayer (which formed the IG Farben conglomerate in 1925) had been producing chlorine as a by-product of their dye manufacturing. In cooperation with Fritz Haber of the Kaiser Wilhelm Institute for Chemistry in Berlin, they began developing methods of discharging chlorine gas against enemy trenches.

By 22 April 1915, the German Army had 168 tons of chlorine deployed in 5,730 cylinders opposite Langemark-Poelkapelle, north of Ypres. At 17:00, in a slight easterly breeze, the gas was released, forming a gray-green cloud that drifted across positions held by French Colonial troops who broke ranks, abandoning their trenches and creating an 8,000 yard (7 km) gap in the Allied line. However, the German infantry were also wary of the gas and, lacking reinforcements, failed to exploit the break before the First Canadian Division and assorted French troops reformed the line in scattered, hastily prepared positions 1,000 to 3,000 yards apart. The Entente governments quickly claimed the attack was a flagrant violation of international law, but Germany argued that the Hague treaty had only banned chemical shells, rather than the use of gas projectors.

90 men died from gas poisoning in the trenches or before they could be got to a dressing station; of the 207 brought to the nearest dressing stations, 46 died almost immediately and 12 after long suffering.

Chlorine is a powerful irritant that can inflict damage to the eyes, nose, throat and lungs. At high concentrations and prolonged exposure it can cause death by asphyxiation.

It quickly became evident that the men who stayed in their places suffered less than those who ran away, as any movement worsened the effects of the gas, and that those who stood up on the fire step suffered less—indeed they often escaped any serious effects—than those who lay down or sat at the bottom of a trench. Men who stood on the parapet suffered least, as the gas was denser near the ground. The worst sufferers were the wounded lying on the ground, or on stretchers, and the men who moved back with the cloud.

Chlorine was, however, less effective as a weapon than the Germans had hoped, particularly as soon as simple counter-measures were introduced. The gas produced a visible greenish cloud and strong odour, making it easy to detect. It was water-soluble, so the simple expedient of covering the mouth and nose with a damp cloth was somewhat effective at reducing the effect of the gas. It was thought to be even more effective to use urine rather than water, as the ammonia would neutralize the chlorine, but it is now known that ammonia and chlorine can produce toxic fumes (NH3 + Cl2 —> HCl + NH2Cl). Even if the chemistry had been correct, the amount of ammonia in human urine is extremely small. However, it was known at the time that chlorine reacted readily with urea (present in large amounts in urine) to form dichlorourea.

Chlorine required a concentration of 1,000 parts per million to be fatal, destroying tissue in the lungs, likely through the formation of hydrochloric (muriatic) acid when dissolved in the water in the lungs (2Cl2 + 2H2O → 4HCl + O2). Despite its limitations, however, chlorine was an effective psychological weapon—the sight of an oncoming cloud of the gas was a continual source of dread for the infantry.

Counter-measures were quickly introduced in response to the use of chlorine gas. The Germans had issued their troops with small gauze pads filled with cotton waste, and bottles of a bicarbonate solution with which to dampen the pads. Immediately following the use of chlorine gas by the Germans, instructions were sent to British and French troops to hold wetted handkerchiefs or cloths over their mouths. Simple pad respirators similar to those issued to German troops were soon proposed by Lieut.-Colonel N.C. Ferguson, the A.D.M.S. of the 28th Division. These pads were intended to be used damp, preferably dipped into a solution of bicarbonate of soda kept in buckets for that purpose, though other liquids were also used. Because such pads could not be expected to arrive at the front for several days, army divisions set about making them for themselves. The locally available muslin, flannel and gauze were used, and officers sent to Paris to buy additional quantities, and local French women were employed making up rudimentary pads with string ties. Other units used lint bandages manufactured in the convent at Poperinge. Pad respirators were sent up with rations to British troops in the line as early as the evening of 24 April.

In Britain the Daily Mail newspaper encouraged women to manufacture cotton pads, and within one month a variety of pad respirators were available to British and French troops, along with motoring goggles to protect the eyes. By 6 July 1915, the entire British army was equipped with the far more effective "smoke helmet" designed by Major Cluny McPherson, Newfoundland Regiment, which was a flannel bag with a celluloid window, which entirely covered the head. The race was then on between the introduction of new and more effective poison gases and the production of effective counter-measures, which marked gas warfare until November 1918.

It is a cowardly form of warfare which does not commend itself to me or other English soldiers.... We cannot win this war unless we kill or incapacitate more of our enemies than they do of us, and if this can only be done by our copying the enemy in his choice of weapons, we must not refuse to do so.

The first use of gas by the British was at the Battle of Loos, 25 September 1915 but the attempt was a disaster. Chlorine, codenamed Red Star, was the agent to be used (140 tons arrayed in 5,100 cylinders), and the attack was dependent on a favorable wind. However, on this occasion the wind proved fickle, and the gas either lingered in no man's land or, in places, blew back on the British trenches.

The British Army had realized that the use of gas was needed, and mounted more gas attacks than the Germans in 1917 and 1918 due to marked increase in production of gas from the Allied nations. Germany was unable to keep up with this pace despite creating various new gases for use in battle, mostly due to very costly methods of production. Entry into the war by the United States allowed the Allies to increase mustard gas production far more than Germany. Also the prevailing wind on the Western Front was from the west, which meant the British more frequently had favorable conditions for a gas release than the Germans.

The deficiencies of chlorine were overcome with the introduction of phosgene, first used by France under the direction of French chemist Victor Grignard in 1915. Colorless and having an odor likened to "mouldy hay," phosgene was difficult to detect, making it a more effective weapon. Although phosgene was sometimes used on its own, it was more often used mixed with an equal volume of chlorine, the chlorine helping to spread the denser phosgene. The Allies called this combination White Star after the marking painted on shells containing the mixture.

Phosgene was a potent killing agent, deadlier than chlorine. It had a potential drawback in that some of the symptoms of exposure took 24 hours or more to manifest. This meant that the victims were initially still capable of putting up a fight; although this could also mean that apparently fit troops would be incapacitated by the effects of the gas on the following day.

In the first combined chlorine/phosgene attack by Germany, against British troops at Nieltje near Ypres, Belgium on 19 December 1915, 88 tons of the gas were released from cylinders causing 1069 casualties and 69 deaths. The British P gas helmet, issued at the time, was impregnated with phenate hexamine and partially effective against phosgene. The modified PH Gas Helmet, which was additionally impregnated with hexamethylenetetramine to improve the protection against phosgene, was issued in January 1916.

Although it was never as notorious in public consciousness as mustard gas, it killed far more people, about 85% of the 100,000 deaths caused by chemical weapons during World War I.

The most widely reported and, perhaps, the most effective gas of the First World War was mustard gas, a vesicant, which was introduced by Germany in July 1917 prior to the Third Battle of Ypres. The Germans marked their shells yellow for mustard gas and green for chlorine and phosgene, so they called the new gas Yellow Cross. It was known to the British as HS (Hun Stuff), while the French called it Yperite (named after Ypres).

Mustard gas was not intended as a killing agent (though in high enough doses it was fatal) but instead was used to harass and disable the enemy and pollute the battlefield. Delivered in artillery shells, mustard gas was heavier than air, and it settled to the ground as an oily sherry-looking liquid. Once in the soil, mustard gas remained active for several days, weeks or even months, depending on the weather conditions.

The polluting nature of mustard gas meant that it was not always suitable for supporting an attack as the assaulting infantry would be exposed to the gas when they advanced. When Germany launched Operation Michael on 21 March 1918, they saturated the Flesquières salient with mustard gas instead of attacking it directly, believing that the harassing effect of the gas, coupled with threats to the salient's flanks, would make the British position untenable.

Gas never reproduced the dramatic success of 22 April 1915; however, it became a standard weapon which, combined with conventional artillery, was used to support most attacks in the later stages of the war. Gas was employed primarily on the Western Front — the static, confined trench system was ideal for achieving an effective concentration — however, Germany made use of gas against Russia on the Eastern Front, where the lack of effective countermeasures would result in deaths of thousands of Russian infantry, while Britain experimented with gas in Palestine during the Second Battle of Gaza.

The skin of victims of mustard gas blistered, their eyes became very sore and they began to vomit. Mustard gas caused internal and external bleeding and attacked the bronchial tubes, stripping off the mucous membrane. This was extremely painful and most soldiers had to be strapped to their beds. It usually took a person four or five weeks to die of mustard gas exposure.

Near the end of the war, the United States began large scale production of an improved vesicant gas known as Lewisite, for use in an offensive planned for the spring of 1919. By the time of the armistice on 11 November, a plant in Ohio was producing 10 tons per day of the substance, for a total of about 150 tons. It is uncertain what effect this new chemical would have had on the battlefield, however, as it degrades in moist conditions.

By the end of the war, chemical weapons had lost much of their effectiveness against well trained and equipped troops. At that time, chemical weapon agents were used in one quarter of artillery shells fired but caused only 3% of casualties.

Nevertheless, in the following years, chemical weapons were used in several, mainly colonial, wars where one side had an advantage in equipment over the other. The British used adamsite against Russian revolutionary troops in 1919 and mustard against Iraqi insurgents in the 1920s; Bolshevik troops used poison gas to suppress the Tambov Rebellion in 1920, Spain used chemical weapons in Morocco against Rif tribesmen throughout the 1920s and Italy used mustard gas in Libya in 1930 and again during its invasion of Ethiopia in 1936. In 1925, a Chinese warlord, Zhang Zuolin, contracted a German company to build him a mustard gas plant in Shenyang, which was completed in 1927.

Public opinion had by then turned against the use of such weapons, which led to the Geneva Protocol, a treaty banning the use (but not the stockpiling) of lethal gas and bacteriological weapons which was signed by most First World War combatants in 1925. Most countries that signed ratified it within around five years, although a few took much longer – Brazil, Japan, Uruguay and the United States did not do so until the 1970s, and Nicaragua ratified it only in 1990.

Although all major combatants stockpiled chemical weapons during the Second World War, the only reports of its use in the conflict were the Japanese use of relatively small amounts of mustard gas and lewisite in China, and very rare occurrences in Europe (for example some sulfur mustard bombs were dropped on Warsaw on 3 September 1939, which Germany acknowledged in 1942 but indicated that it had been accidental). Mustard gas was the agent of choice, with the British stockpiling 40,719 tons, the Russians 77,400 tons, the Americans over 87,000 tons and the Germans 27,597 tons.

The mustard gas with which the British hoped to repel an invasion of the United Kingdom in 1940 was never needed, and a fear that the Allies also had nerve agents (in fact the Allies were not aware of them until the discovery of German stockpiles) prevented their deployment by Germany. Nevertheless poison gas technology played an important role in the Holocaust.

Although chemical weapons have been used in at least a dozen wars since the end of the First World War, they have never been used again in combat on such a large scale. Nevertheless, the use of mustard gas and the more deadly nerve agents by Iraq during the 8-year Iran-Iraq war killed around 20,000 Iranian troops (and injured another 80,000), around a quarter of the number of deaths caused by chemical weapons during the First World War.

The contribution of gas weapons to the total casualty figures was relatively minor. British figures, which were accurately maintained from 1916, recorded that only 3% of gas casualties were fatal, 2% were permanently invalid and 70% were fit for duty again within six weeks. All gas casualties were mentally scarred by exposure, and gas remained one of the great fears of the front-line soldier.

It was remarked as a joke that if someone yelled 'Gas', everyone in France would put on a mask. ... Gas shock was as frequent as shell shock.

Gas! GAS! Quick, boys! - An ecstasy of fumbling, Fitting the clumsy helmets just in time; But someone still was yelling out and stumbling, And flound'ring like a man in fire or lime... Dim, through the misty panes and thick green light, As under a green sea, I saw him drowning. In all my dreams, before my helpless sight, He plunges at me, guttering, choking, drowning.

Mustard gas caused the most gas casualties on the Western Front, despite being produced in smaller quantities than inhalant gases such as chlorine and phosgene. The proportion of mustard gas fatalities to total casualties was low; only 2% of mustard gas casualties died and many of these succumbed to secondary infections rather than the gas itself. Once it was introduced at the third battle of Ypres, mustard gas produced 90% of all British gas casualties and 14% of battle casualties of any type.

Mustard gas did not need to be inhaled to be effective — any contact with skin was sufficient. Exposure to 0.1 ppm was enough to cause massive blisters. Higher concentrations could burn flesh to the bone. It was particularly effective against the soft skin of the eyes, nose, armpits and groin, since it dissolved in the natural moisture of those areas. Typical exposure would result in swelling of the conjunctiva and eyelids, forcing them closed and rendering the victim temporarily blind. Where it contacted the skin, moist red patches would immediately appear which after 24 hours would have formed into blisters. Other symptoms included severe headache, elevated pulse and temperature (fever), and pneumonia (from blistering in the lungs).

Case four. Aged 39 years. Gassed 29 July 1917. Admitted to casualty clearing station the same day. Died about ten days later. Brownish pigmentation present over large surfaces of the body. A white ring of skin where the wrist watch was. Marked superficial burning of the face and scrotum. The larynx much congested. The whole of the trachea was covered by a yellow membrane. The bronchi contained abundant gas. The lungs fairly voluminous. The right lung showing extensive collapse at the base. Liver congested and fatty. Stomach showed numerous submucous haemorrhages. The brain substance was unduly wet and very congested.

They cannot be bandaged or touched. We cover them with a tent of propped-up sheets. Gas burns must be agonizing because usually the other cases do not complain even with the worst wounds but gas cases are invariably beyond endurance and they cannot help crying out.

Many of those who survived a gas attack were scarred for life. Respiratory disease and failing eye sight were common post-war afflictions. Of the Canadians who, without any effective protection, had withstood the first chlorine attacks during 2nd Ypres, 60% of the casualties had to be repatriated and half of these were still unfit by the end of the war, over three years later.

In reading the statistics of the time, one should bear the longer term in mind. Many of those who were fairly soon recorded as fit for service were left with scar tissue in their lungs. This tissue was susceptible to tuberculosis attack. It was from this that many of the 1918 casualties died, around the time of the Second World War, shortly before sulfa drugs became widely available for its treatment.

One notable poison gas casualty of World War I was Adolf Hitler, who was temporarily blinded. As a result, Hitler adamantly refused to authorise the use of poison gas on the battlefield during World War II, for fear of retaliation. However, poison gas agents such as carbon monoxide and Zyklon B were extensively used against civilians in extermination camps.

None of the First World War's combatants were prepared for the introduction of poison gas as a weapon. Once gas had appeared, development of gas protection began and the process continued for much of the war producing a series of increasingly effective gas masks.

Even at Second Ypres, Germany, still unsure of the weapon's effectiveness, only issued breathing masks to the engineers handling the gas. At Ypres a Canadian medical officer, who was also a chemist, quickly identified the gas as chlorine and recommended that the troops urinate on a cloth and hold it over their mouth and nose, the theory being the uric acid would crystallize the chlorine. The first official equipment issued was similarly crude; a pad of material, usually impregnated with a chemical, tied over the lower face. To protect the eyes from tear gas, soldiers were issued with gas goggles.

The goggles rapidly dimmed over, and the air came through in such suffocatingly small quantities as to demand a continuous exercise of will-power on the part of the wearers.

A modified version of the P Helmet, called the PH Helmet, was issued in January 1916, and was additionally impregnated with hexamethylenetetramine to improve the protection against phosgene.

Self-contained box respirators represented the culmination of gas mask development during the First World War. Box respirators used a two-piece design; a mouthpiece connected via a hose to a box filter. The box filter contained granules of chemicals that neutralised the gas, delivering clean air to the wearer. Separating the filter from the mask enabled a bulky but efficient filter to be supplied. Nevertheless, the first version, known as the Large Box Respirator (LBR) or "Harrison's Tower", was deemed too bulky — the "box" canister needed to be carried on the back. The LBR had no mask, just a mouthpiece and nose clip; separate gas goggles had to be worn. It continued to be issued to the artillery gun crews but the infantry were supplied with the "Small Box Respirator" (SBR).

The Small Box Respirator featured a single-piece, close-fitting rubberized mask with eye-pieces. The box filter was compact and could be worn around the neck. The SBR could be readily upgraded as more effective filter technology was developed. The British-designed SBR was also adopted for use by the American Expeditionary Force. The SBR was the prized possession of the ordinary infantryman; when the British were forced to retreat during the German Spring Offensive of 1918, it was found that while some troops had discarded their rifles, hardly any had left behind their respirators.

It was not only humans that needed protection from gas; horses and mules, which were the main means of transport, were also vulnerable to gas and needed to be provided with protection. As animals were never used near the front-line, protection from gas only became necessary when the practice of firing gas shells into rear areas was adopted.

For mustard gas, which did not need to be inhaled in order to inflict casualties, no effective countermeasure was found during the war. The kilt-wearing Scottish regiments were especially vulnerable to mustard gas injuries due to their bare legs. At Nieuwpoort in Flanders some Scots battalions took to wearing women's tights beneath the kilt as a form of protection.

The Canadian soldiers are said to have found a way to minimize the effects of the mustard gas. Since the gas was sent by the wind towards them, they understood that it would minimize the exposure to the gas if the Canadians not only did not flee but ran through the gas. The French, conversely, when the gas was first used against them, fled, and therefore spent more time in the gas, suffering greater casualties.

Gas alert procedure became a routine for the front-line soldier. To warn of a gas attack, a bell would be rung, often made from a spent artillery shell. At the noisy batteries of the siege guns, a compressed air strombus horn was used, which could be heard nine miles (14 km) away. Notices would be posted on all approaches to an affected area, warning people to take precautions.

Other British attempts at countermeasures were not so effective. An early plan was to use 100,000 fans to disperse the gas. Burning coal or carborundum dust was tried. A proposal was made to equip front-line sentries with diving helmets, air being pumped to them through a 100 ft (30 m) hose.

However, the effectiveness of all countermeasures is apparent. In 1915, when poison gas was relatively new, less than 3% of British gas casualties died. In 1916, the proportion of fatalities jumped to 17%. By 1918, the figure was back below 3%, though the total number of British gas casualties was now nine times the 1915 levels.

The first system employed for the mass delivery of gas involved releasing the gas from cylinders in a favourable wind such that it was carried over the enemy's trenches. The main advantage of this method was that it was relatively simple and, in suitable atmospheric conditions, produced a concentrated cloud capable of overwhelming the gas mask defences. The disadvantages of cylinder releases were numerous. First and foremost, delivery was at the mercy of the wind. If the wind was fickle, as was the case at Loos, the gas could backfire, causing friendly casualties. Gas clouds gave plenty of warning, allowing the enemy time to protect themselves, though many soldiers found the sight of a creeping gas cloud unnerving. Also gas clouds had limited penetration, only capable of affecting the front-line trenches before dissipating.

Finally, the cylinders had to be emplaced at the very front of the trench system so that the gas was released directly over no man's land. This meant that the cylinders had to be manhandled through communication trenches, often clogged and sodden, and stored at the front where there was always the risk that cylinders would be prematurely breached during a bombardment. A leaking cylinder could issue a telltale wisp of gas that, if spotted, would be sure to attract shellfire.

A British chlorine cylinder, known as an "oojah", weighed 190 lb (86 kg), of which only 60 lb (27 kg) was chlorine gas, and required two men to carry. Phosgene gas was introduced later in a cylinder, known as a "mouse", that only weighed 50 lb (23 kg).

Delivering gas via artillery shell overcame many of the risks of dealing with gas in cylinders. The Germans, for example, used 5.9-inch (150 mm) artillery shells. Gas shells were independent of the wind and increased the effective range of gas, making anywhere within reach of the guns vulnerable. Gas shells could be delivered without warning, especially the clear, nearly odorless phosgene — there are numerous accounts of gas shells, landing with a "plop" rather than exploding, being initially dismissed as dud HE or shrapnel shells, giving the gas time to work before the soldiers were alerted and took precautions.

The main flaw associated with delivering gas via artillery was the difficulty of achieving a killing concentration. Each shell had a small gas payload and an area would have to be subjected to a saturation bombardment to produce a cloud to match cylinder delivery. Mustard gas, however, did not need to form a concentrated cloud and hence artillery was the ideal vehicle for delivery of this battlefield pollutant.

The solution to achieving a lethal concentration without releasing from cylinders was the "gas projector", essentially a large-bore mortar that fired the entire cylinder as a missile. The British Livens projector (invented by Captain W.H. Livens in 1917) was a simple device; an 8-inch (200 mm) diameter tube sunk into the ground at an angle, a propellant was ignited by an electrical signal, firing the cylinder containing 30 or 40 lb (14 or 18 kg) of gas up to 1,900 meters. By arranging a battery of these projectors and firing them simultaneously, a dense concentration of gas could be achieved. The Livens was first used at Arras on 4 April 1917. On 31 March 1918 the British conducted their largest ever "gas shoot", firing 3,728 cylinders at Lens.

Over 16,000,000 acres (65,000 km2) of France had to be cordoned off at the end of the war because of unexploded ordnance. About 20% of the chemical shells were duds, and approximately 13 million of these munitions were left in place. This has been a serious problem in former battle areas from immediately after the end of the War until the present. Shells may be, for instance, uncovered when farmers plough their fields (termed the 'iron harvest'), and are also regularly discovered when public works or construction work is done.

An additional difficulty is the current stringency of environmental legislation. In the past, a common method of getting rid of unexploded chemical ammunition was to detonate or dump it at sea; this is currently prohibited in most countries.

The problems are especially acute in some northern regions of France. The French government no longer disposes of chemical weapons at sea. For this reason, piles of untreated chemical weapons accumulated. In 2001, it became evident that the pile stored at a depot in Vimy was unsafe; the inhabitants of the neighboring town were evacuated, and the pile moved, using refrigerated trucks and under heavy guard, to a military camp in Suippes. The capacity of the plant is meant to be 25 tons per year (extensible to 80 tons at the beginning), for a lifetime of 30 years.

Germany has to deal with unexploded ammunition and polluted lands resulting from the explosion of an ammunition train in 1919.

Nevertheless, precautions were taken in World War II. In both Axis and Allied nations, children in school were taught to wear gas masks in case of gas attack. Italy did use poison gas against Ethiopia in 1935 and 1936, and the Empire of Japan used gas against China in 1941. Germany developed the poison gases tabun, sarin, and soman during the war, and, infamously, used Zyklon B in Nazi extermination camps. Neither Germany nor the Allied nations used any of their war gases in combat, despite maintaining large stockpiles and occasional calls for their use, possibly heeding warnings of awful retaliation. The United States did consider using gas to support their planned invasion of Japan.

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Ideal gas

The ideal gas model is a model of matter in which the molecules are treated as non-interacting point particles which are engaged in a random motion that obeys conservation of energy. At standard temperature and pressure, most real gases behave qualitatively like an ideal gas: for example, 22.4 liters of most gases at standard temperature and pressure will contain very nearly 6.022 × 1023 molecules (one mole).

The model tends to fail at lower temperatures or higher pressures, when the molecules come close enough that they start interacting with each other, and not just with their surroundings. This is usually associated with a phase transition. For example, clouds form when the gas of water molecules in the sky drops below the dew point, which causes the water molecules to "stick together" into little droplets. By contrast, at high temperatures and low pressures, the vast majority of familiar substances can be vaporised and will behave more-or-less as an ideal gas.

The ideal gas model has been explored in both the Newtonian dynamics (as "kinetic theory") and in quantum mechanics (as a "gas in a box"). The model has also been used to model the behavior of electrons in a metal (in the Drude model and free electron model) and is one of the most important models in statistical mechanics.

The classical ideal gas can be separated into two types: The classical thermodynamic ideal gas and the ideal quantum Boltzmann gas. Both are essentially the same, except that the classical thermodynamic ideal gas is based on classical thermodynamics alone, and certain thermodynamic parameters such as the entropy are only specified to within an undetermined additive constant. The ideal quantum Boltzmann gas overcomes this limitation by taking the limit of the quantum Bose gas and quantum Fermi gas in the limit of high temperature to specify these additive constants. The behavior of a quantum Boltzmann gas is the same as that of a classical ideal gas except for the specification of these constants. The results of the quantum Boltzmann gas are used in a number of cases including the Sackur-Tetrode equation for the entropy of an ideal gas and the Saha ionization equation for a weakly ionized plasma.

The thermodynamic properties of an ideal gas can be described by two equations : The equation of state of a classical ideal gas is given by the ideal gas law.

The probability distribution of particles by velocity or energy is given by the Boltzmann distribution.

The ideal gas law is an extension of experimentally discovered gas laws. Real fluids at low density and high temperature approximate the behavior of a classical ideal gas. However, at lower temperatures or a higher density, a real fluid deviates strongly from the behavior of an ideal gas, particularly as it condenses from a gas into a liquid or solid. The deviation is expressed as a compressibility factor.

It is seen that the constant is just the dimensionless heat capacity at constant volume. It is equal to half the number of degrees of freedom per particle. For moderate temperatures, the constant for a monoatomic gas is while for a diatomic gas it is . It is seen that macroscopic measurements on heat capacity provide information on the microscopic structure of the molecules.

Using the results of thermodynamics only, we can go a long way in determining the expression for the entropy of an ideal gas. This is an important step since, according to the theory of thermodynamic potentials, of which the internal energy U is one, if we can express the entropy as a function of U and the volume V, then we will have a complete statement of the thermodynamic behavior of the ideal gas. We will be able to derive both the ideal gas law and the expression for internal energy from it.

This is about as far as we can go using thermodynamics alone. Note that the above equation is flawed — as the temperature approaches zero, the entropy approaches negative infinity, in contradiction to the third law of thermodynamics. In the above "ideal" development, there is a critical point, not at absolute zero, at which the argument of the logarithm becomes unity, and the entropy becomes zero. This is unphysical. The above equation is a good approximation only when the argument of the logarithm is much larger than unity — the concept of an ideal gas breaks down at low values of V/N. Nevertheless, there will be a "best" value of the constant in the sense that the predicted entropy is as close as possible to the actual entropy, given the flawed assumption of ideality. It remained for quantum mechanics to introduce a reasonable value for the value of φ which yields the Sackur-Tetrode equation for the entropy of an ideal gas. It too suffers from a divergent entropy at absolute zero, but is a good approximation to an ideal gas over a large range of densities.

In statistical mechanics, the relationship between the Helmholtz free energy and the partition function is fundamental, and is used to calculate the thermodynamic properties of matters; see configuration integral for more details.

See Table of thermodynamic equations#Equation Table for an Ideal Gas.

An ideal gas of bosons (e.g. a photon gas) will be governed by Bose-Einstein statistics and the distribution of energy will be in the form of a Bose-Einstein distribution. An ideal gas of fermions will be governed by Fermi-Dirac statistics and the distribution of energy will be in the form of a Fermi-Dirac distribution.

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Source : Wikipedia