States of matter
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How do I describe the solubility of hydrogen gas in water, and describe its relative density?
Jenkin replies:
The solubility of a gas is described by its absorption coefficient. This is defined as the volume of gas, measured at 273 K and 1 atm pressure, which will dissolve in unit volume of the solvent at a stated temperature under a partial pressure of 1 atm.
For hydrogen in water, the absorption coefficient is 0.021, which indicates a low solubility - 0.021 dm3 (or 21 cm3) of H2 in 1 dm3 of water.
Relative density (a quantity rarely used nowadays) is the ratio of the mass of a given volume of gas to the mass of an equal volume of hydrogen at the same temperature and pressure. So the relative density of hydrogen is 1, by definition. Because it is a relative quantity it has no units.
Risk assessment
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updated: 29 May 2007
