Guides for Emergency Response Chemical Agents and Weapons

In the standard format used for each Chemical agent on the following pages, the following definitions apply. 

Formula An expression of the constituents of a compound by symbols and figures. 

Vapor Density The ratio of the density of any gas or vapor to the density of air, under the same conditions of temperature and pressure that is, a measure of how heavy the vapor is in relation to the same volume of air. Air is considered to have a molecular weight of 1. As an example, the higher the vapor density is in relation to 1.0, the longer it will persist in low-lying areas such as valleys, trenches, and cellar holes. If the vapor pressure is less than 1, a chemical agent would will likely be non-persistent and dissipate quickly into the atmosphere. 

Vapor Pressure A measure of the tendency of a liquid to become a gas at a given temperature. Chemical agents with a high vapor pressure evaporate rapidly, while those with a low vapor pressure evaporate more slowly. 

Volatility Passing off rapidly in the form of vapor evaporating rapidly. It provides a measure of how much material evaporates under given conditions and varies directly with temperature. The volatility depends on vapor pressure. 

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Guides for Emergency Response Chemical Agents and Weapons... 

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