Fugacity of an Ideal Mixture

A relationship for the fugacity of species i in an ideal mixture is derived in a similar way as for the state properties. 

A comparison of Eqs. (4.60) and (4.67) shows that the fugacity of a component in an ideal mixture is calculated from the fugacity of the pure component multiplied by the mole fraction  

This equation is also known as the Lewis-Randall rule. 

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