Henrys law and the solubility of gases

Equation (14.26) relates pj in dilute solution to Cj, the concentration in mol/L. It is not as commonly used as Eq. (14.23) p° is the chemical potential the solute would have at a concentration of 1 mol/L if the solution behaved ideally up to that concentration. 

The second term in Eq. (14.27) becomes (8.314 J/K mol)(298.15 K) In (1.002965) = 7.339 J/mol. In most cases, this is less than the uncertainties in the experimental values so that the difference between the mj and Cj standard states can be ignored. 

Henry s law, Eq. (14.16), relates the partial pressure of the solute in the vapor phase to the mole fraction of the solute in the solution. Viewing the relation in another way, Henry s law relates the equilibrium mole fraction, the solubility of j in the solution, to the partial pressure of j in the vapor  

Equation (14.28) states that the solubility Xj of a volatile constituent is proportional to the partial pressure of that constituent in the gaseous phase in equilibrium with the liquid. Equation (14.28) is used to correlate the data on solubility of gases in liquids. If the solvent and gas do not react chemically, the solubility of gases in liquids is usually small and the condition of diluteness is fulfilled. Here we have another example of the physical significance of the partial pressure. 

The solubility of gases is often expressed as the Bunsen absorption coefficient, a, which is the volume of gas, measured at 0 °C and 1 atm, dissolved by unit volume of solvent if the partial pressure of the gas is 1 atm. 

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