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The ideal gas law, or universal gas equation, is an equation of state of an ideal gas. It combines several gas laws.- pV = nRT
Here p is the pressure of gas, V the volume it occupies, n the number of moles of gas, R the molar gas constant, and T the temperature of the gas. In SI units, the pressure is expressed in pascals, the volume in cubic metres, and the temperature in kelvin. The ideal gas law generalizes the three classical gas laws.
The equation is valid only for an ideal gas. Real gases obey this equation only approximately, but its validity increases as the density of the gas tends to zero.
The picture shows some isotherms of an ideal gas (i.e. the relation between pressure p and volume V at fixed temperature T; plotted for a set of temperatures, with increasing T from lower to upper curve):
This law is favoured only at certain range of temperature and pressure. Remember this is not a robust law for gases which determines the physical nature of gases universally at all conditions. A more appropriate way to determine the physical characteristics of gases is by the Van der Waals equation. This equation can be used at wider range of temperature and pressure. See more on Real Gases.
See also
- Equation of StateIn physics, equations of state attempt to describe the relationship between temperature, pressure, and volume for a given substance or mixture of substances. An equation of state may be viewed as a type of constitutive equation. The ideal gas law, shown b
- Van der Waals equation
ThermodynamicsThermodynamics is the physics of energy, heat, work, entropy and the spontaneity of processes. Thermodynamics is closely related to statistical mechanics from which many thermodynamic relationships can be derived. While dealing with processes in which sys
