# gas laws

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Related to Ideal-gas law: Ideal gas equation, Pv=nrt

## 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.
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.
. 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;.
. 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.
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,
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.