The USSA1976 acknowledges that this value is not consistent with the cited values for the Avogadro constant and the Boltzmann constant.

Note the use of kilomoles, with the resulting factor of 1000 in the constant. Then the molar mass of air is computed by M 0 = R/ R air = 28.964 917 g/mol.

In case of air, using the perfect gas law and the standard sea-level conditions (SSL) (air density ρ 0 = 1.225 kg/m 3, temperature T 0 = 288.15 K and pressure p 0 = 101 325 Pa), we have that R air = P 0/( ρ 0 T 0) = 287.052 874 247 J In any case, the context and/or unit of the gas constant should make it clear as to whether the universal or specific gas constant is being referred to. In such cases, the universal gas constant is usually given a different symbol such as R to distinguish it. It is common, especially in engineering applications, to represent the specific gas constant by the symbol R. Where c p is the specific heat capacity for a constant pressure and c v is the specific heat capacity for a constant volume. The gas constant R is defined as the Avogadro constant N A multiplied by the Boltzmann constant k (or k B): The Boltzmann constant and the Avogadro constant were similarly determined, which separately relate energy to temperature and particle count to amount of substance. Thus, the value of the gas constant ultimately derives from historical decisions and accidents in the setting of units of energy, temperature and amount of substance. The gas constant is the constant of proportionality that relates the energy scale in physics to the temperature scale and the scale used for amount of substance. It is a physical constant that is featured in many fundamental equations in the physical sciences, such as the ideal gas law, the Arrhenius equation, and the Nernst equation. The constant is also a combination of the constants from Boyle's law, Charles's law, Avogadro's law, and Gay-Lussac's law. the pressure–volume product, rather than energy per temperature increment per particle.

It is the molar equivalent to the Boltzmann constant, expressed in units of energy per temperature increment per amount of substance, i.e. The molar gas constant (also known as the gas constant, universal gas constant, or ideal gas constant) is denoted by the symbol R or R. Under standard conditions (25 oC, 1atm), the density of air is about 1.168kgm -3.Physical constant equivalent to the Boltzmann constant, but in different units Value of R to get 1kg of oxygen, we need 1/0.2320 = 4.31kg of air). The 'Mass Ratio' is useful for combustion calculations (e.g. Since both of these elements are diatomic in air - O 2 and N 2, the molecular mass of Oxygen is 32 and the molecular mass of Nitrogen is 28.Īir is a mixture of gases and the total mass can be estimated by adding the weight of all major components as shown here: Oxygen has a 16 atomic unit mass and Nitrogen has a 14 atomic units mass. The two most dominant components in dry air are Oxygen and Nitrogen.

Molar mass of o2