gas laws

Also found in: Dictionary, Thesaurus, Medical, Wikipedia.

gas laws,

physical laws describing the behavior of a gasgas,
in physics, one of the three commonly recognized states of matter, the other two being solid and liquid. A substance in the gaseous state has neither definite shape nor definite volume. Like liquids, gases are fluids and assume the shape of their containers.
..... Click the link for more information.
 under various conditions of pressure, volume, and temperature. Experimental results indicate that all real gases behave in approximately the same manner, having their volume reduced by about the same proportion of the original volume for each drop of 1° on the Celsius temperature scaleCelsius temperature scale
, temperature scale according to which the temperature difference between the reference temperatures of the freezing and boiling points of water is divided into 100 degrees.
..... Click the link for more information.
. Graphs drawn to describe this behavior can be extrapolated, and all converge to a point corresponding to about −273°C; (−459°F;)—this point is called absolute zeroabsolute zero,
the zero point of the ideal gas temperature scale, denoted by 0 degrees on the Kelvin and Rankine temperature scales, which is equivalent to −273.15°C; and −459.67°F;.
..... Click the link for more information.
. A temperature scale defined so that zero degrees corresponds to this zero-volume temperature coordinate is known as an absolute scale. The Kelvin temperature scaleKelvin temperature scale,
a temperature scale having an absolute zero below which temperatures do not exist. Absolute zero, or 0°K;, is the temperature at which molecular energy is a minimum, and it corresponds to a temperature of −273.
..... Click the link for more information.
 begins at this absolute zero and has degrees the same size as those of the Celsius scale.

Gas Laws Relating Two Variables

The simplest gas laws relate pressure, volume, and temperature in pairs. Boyle's law (advanced by Robert Boyle in 1662) states that the pressure and volume of a gas are inversely proportional to one another, or PV = k, where P is pressure, V is volume, and k is a constant of proportionality. Charles's law (published by Jacques A. C. Charles in 1787), sometimes known as Gay-Lussac's law (independently demonstrated by Joseph Gay-Lussac in 1802), states that the volume of an enclosed gas is directly proportional to its temperature, or V = kT. This expression is strictly true only if the temperature is measured on an absolute scale. A third law states that the pressure is directly proportional to the absolute temperature, or P = kT.

Gas Laws Relating Three Variables

The three gas laws relating two variables can be combined into a single law relating pressure, temperature, and volume, which states that the product of pressure and volume is directly proportional to the absolute temperature, or PV = kT. This law describes the behavior of real gases only with a certain range of values for the variables. At temperatures or pressures near those at which the gas condenses to a liquid, the behavior departs from this equation. Nevertheless, it is useful to consider an ideal gas, or perfect gas, an imaginary substance that conforms to this equation for all values of the variables.

The behavior of an ideal gas can be described in terms of the kinetic-molecular theory of gaseskinetic-molecular theory of gases,
physical theory that explains the behavior of gases on the basis of the following assumptions: (1) Any gas is composed of a very large number of very tiny particles called molecules; (2) The molecules are very far apart compared to their sizes,
..... Click the link for more information.
 and leads directly to the relationship PV = kT, which is therefore called the ideal gas law, or general gas law. The constant of proportionality k is usually expressed as the product of the number of molesmole,
in chemistry, a quantity of particles of any type equal to Avogadro's number, or 6.02×1023 particles. One gram-molecular weight of any molecular substance contains exactly one mole of molecules.
..... Click the link for more information.
, n, of the gas and a constant R, known as the universal gas constant. In MKS units, R has the value 8.3149 × 103 joules/kilogram-mole-degree. The ideal gas law can be further simplified by replacing the ordinary volume V by the specific volume v, which is equal to V/n. The law then has the form Pv = RT. This form has the advantage that all of the variables are intensive; that is, none of the variables depends on the mass of the gas.

The van der Waals equation (for the Dutch physicist Johannes van der Waals) is another gas law involving pressure, temperature, and volume. It takes into account the variations in behavior of different real gases from that of an ideal gas. The van der Waals equation is usually given as (P + a/v2)(vb) = RT, where a and b are constants that have different particular values for different real gases. Other, more complicated equations exist that describe the behavior of real gases over an even wider range of values for pressure, temperature, and volume.

See also thermodynamicsthermodynamics,
branch of science concerned with the nature of heat and its conversion to mechanical, electric, and chemical energy. Historically, it grew out of efforts to construct more efficient heat engines—devices for extracting useful work from expanding hot gases.
..... Click the link for more information.

References in periodicals archive ?
As your front man at the pumps, I think that the next time you're cooking up a new gas law, I should have some say in the matter.
The density of the gas used usually increases considerably (such that even ideal gas laws may not further be applicable).
The first concise presentation of physical chemistry as a logical sequence from its most modest beginning in the gas laws and thermodynamics through solution chemistry to contemporary research topics such as electrochemical cells, computational kinetics, and photochemistry
Walker represented the President of the Republic of Bolivia in Bolivia's successful effort to rewrite its oil and gas laws and capitalize (a form of privatization) its national oil company.
The 28 experiments include specific heats of substances, chromatography, reaction stoichiometry, gravimetric analysis of a chloride compound, the concentration of acetic acid in vinegar, colligative properties, and gas laws.
These risks and uncertainties include but are not limited to the continuing ability of the Company to operate effectively internationally, reliance on current oil and gas laws, rules and regulations, volatility of oil and gas prices, fluctuations in currency and interest rates, imprecision of resource estimates, the results of exploration, development and drilling, imprecision in estimates of future production capacity, changes in environmental and other regulations or the interpretation of such regulations, the ability to obtain necessary regulatory approvals, weather and general economic and business conditions.
Details of the assets, including geological cross-sections, well log data from neighboring fields, and links to the State of Alaska's oil and gas laws, are currently available on IndigoPool.
com), a Schlumberger company, today announced its agreement with the Barrows Company to make available the world's most comprehensive library of oil and gas laws and contracts from virtually every country outside North America.