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vapour density = molar mass of gas / molar mass of H 2 vapour density = molar mass of gas / 2.01568 vapour density = 1 ⁄ 2 × molar mass (and thus: molar mass = ~2 × vapour density) For example, vapour density of mixture of NO 2 and N 2 O 4 is 38.3. Vapour density is a dimensionless quantity. Vapour density = density of gas / density of ...
Dumas used the method to determine the vapour densities of elements (mercury, phosphorus, sulfur) and inorganic compounds. [3] Today, modern methods such as mass spectrometry and elemental analysis are used to determine the molecular weight of a substance.
This principle is included in the ideal gas equation: =, where n is the amount of substance. The vapour density (ρ) is given by =. Combining these two equations gives an expression for the molar mass in terms of the vapour density for conditions of known pressure and temperature:
The saturation vapor density (SVD) is the maximum density of water vapor in air at a given temperature. [1] The concept is related to saturation vapor pressure (SVP). It can be used to calculate exact quantity of water vapor in the air from a relative humidity (RH = % local air humidity measured / local total air humidity possible ) Given an RH percentage, the density of water in the air is ...
The van der Waals equation is a mathematical formula that describes the behavior of real gases. It is named after Dutch physicist Johannes Diderik van der Waals . It is an equation of state that relates the pressure , temperature , and molar volume in a fluid .
The vapour displaces its own volume of air. The volume of air displaced at experimental temperature and pressure is calculated. Then volume of air displaced at standard temperature and pressure is calculated. Using this, mass of air displaced at 2.24 × 10 −2 m 3 of vapour at STP is calculated. This value represents the molecular mass of the ...
Here is a similar formula from the 67th edition of the CRC handbook. Note that the form of this formula as given is a fit to the Clausius–Clapeyron equation, which is a good theoretical starting point for calculating saturation vapor pressures: log 10 (P) = −(0.05223)a/T + b, where P is in mmHg, T is in kelvins, a = 38324, and b = 8.8017.
The Kelvin equation describes the change in vapour pressure due to a curved liquid–vapor interface, such as the surface of a droplet. The vapor pressure at a convex curved surface is higher than that at a flat surface. The Kelvin equation is dependent upon thermodynamic principles and does not allude to special properties of materials.