**Vapour density** is the density of a vapour in relation to that of hydrogen. It may be defined as mass of a certain volume of a substance divided by mass of same volume of hydrogen.

vapour density = mass of *n* molecules of gas / mass of *n* molecules of hydrogen

Therefore:

vapour density = molar mass of gas / molar mass of H_{2}

vapour density = molar mass of gas / 2.0016

vapour density = ~½ × molar mass

(and thus: molar mass = ~2 × vapour density)

Read more about Vapour Density: Alternative Definition

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**Vapour Density**- Alternative Definition

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**vapour density**relies on the principle, first enunciated by Amadeo Avogadro, that equal volumes of gases under identical conditions contain equal numbers of particles ... 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 ...### Famous quotes containing the word vapour:

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