Henrys Law, Gas Solubility

The partial separation of a gas component / (absorptive i) from a gas mixture is usually done using a liquid solvent (absorbent). The 

To find a concept to describe the technical importance of gas solubility, the mixture is assumed to be infinitely dilute, or an ideally diluted solution. With a large excess of solvent, when the gas component i is dissolved, the mole fraction x,- in the solution tends to 0 (x, - 0). At vapor-liquid equilibrium, Henry s law for an ideally diluted solution may be applied to the gas solubility of component / in the solvent 

In an ideally diluted solution, the partial pressure p, of the gas component i is proportional to the mole fraction x, in the solution. The constant of proportionality is Henry s constant Hj, which is dependent on temperature, pressure, and the respective excess component. Van-der-Waals forces in the solvent bond the gas component / in the solution the gas component / is physically dissolved. 

Henry s and Raoult s laws are only valid under limited conditions (see Fig. 1-26). Raoult s law gives an asymptote to the real partial pressure curve p, (x,) where x, - l. Henry s law gives the tangent of the partial pressure curve at the limit x, -+0. 

Henry s law is only really valid for gases which are sparingly soluble. A small mole fraction of dissolved gas / leads to a considerable deviation from the linear relationship between the partial pressure p, and the mole fraction x,. For this reason x,- is cor- 

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