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From the ideal gas law PV = nRT we get: = where P is pressure, V is volume, n is number of moles of a given substance, and T is temperature. As pressure is defined as force per area of measurement, the gas equation can also be written as:
Quantity (common name/s) (Common) symbol/s Defining equation SI unit Dimension General heat/thermal capacity C = / J⋅K −1: ML 2 T −2 Θ −1: Heat capacity (isobaric)
In physics, the thermal equation of state is a mathematical expression of pressure P, temperature T, and, volume V.The thermal equation of state for ideal gases is the ideal gas law, expressed as PV=nRT (where R is the gas constant and n the amount of substance), while the thermal equation of state for solids is expressed as:
Isotherms of an ideal gas for different temperatures. The curved lines are rectangular hyperbolae of the form y = a/x. They represent the relationship between pressure (on the vertical axis) and volume (on the horizontal axis) for an ideal gas at different temperatures: lines that are farther away from the origin (that is, lines that are nearer to the top right-hand corner of the diagram ...
The table below displays densities and specific volumes for various common substances that may be useful. The values were recorded at standard temperature and pressure, which is defined as air at 0 °C (273.15 K, 32 °F) and 1 atm (101.325 kN/m 2 , 101.325 kPa, 14.7 psia, 0 psig, 30 in Hg, 760 torr).
All data used in this section were obtained from the NIST Chemistry WebBook. [8] It is useful to note that for N 2 the normal boiling point of the liquid is 77.4 K and the critical point is at 126.2 K and 34.0 bar. Overview of the temperature and pressure dependence of the compressibility factor for N 2
The terms perfect gas and ideal gas are sometimes used interchangeably, depending on the particular field of physics and engineering. Sometimes, other distinctions are made, such as between thermally perfect gas and calorically perfect gas, or between imperfect, semi-perfect, and perfect gases, and as well as the characteristics of ideal gases.
where H = U + PV is the enthalpy of the gas. Sometimes, a distinction is made between an ideal gas, where ĉ V and ĉ P could vary with temperature, and a perfect gas, for which this is not the case. The ratio of the constant volume and constant pressure heat capacity is the adiabatic index =