Theoretical Principles of Absorption

ABSORPTION OF HYDROGEN CHLORIDE IN WATER 1. Theoretical principles of absorption 

A given amount of liquid can absorb gas only up to the concentration at which the partial pressure of the gas from the solution formed by absorption is equal to its partial pressure in the gas phase. If the partial pressure of the gas from the solution is lower than in the vapour phase, absorption sets in and the rate of absorption, at a given total absorption coefficient, depends on the difference in the partial pressures in the two phases and on the size of the contact surface. From the dependence of the partial pressures of hydrogen chloride on the composition of the hydrochloric acid it follows that the vapour pressure of HC1 from diluted solutions is relatively very low. Therefore, praotically all the hydrogen chloride from the gas phase can be absorbed, as 

Vapour pressures of IJC1 from hydrochloric acid. 

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