Henry s law for adsorption

This general relation between n, the moles adsorbed, and P, the gas-phase pressnre, inclndes z, the adsorbate compressibility factor, wliich may be represented by an equation of state for the adsorbate. The simplest such equation is the ideal-gas analog, Z = I, and in this case Eq. (14.105) yields n = kP, which is Henry s law for adsorption. 

The slope of this line is often referred to as Henry s constant, and Expression 6.5d as Henry s law for adsorption, in analogy to the corresponding case of gas-liquid equilibrium (see Equation 6.2). 

---