Is there a term/quantity which shows how 'sticky/adsorptive' a molecule is? I am interested in gas adsorption on steel surfaces in our mass spectrometer and would like to estimate which gases have a higher propensity to adsorb.


1 Answer 1


The term you are looking for is "adsorption enthalpy". However calculating that value will depend on a variety of factors mainly the absorbate and substrate, but it is not that simple. The surface structure of substrates matters and a $[111]$ oriented crystallographic face will have a different adsorption enthalpy with a given absorbate that say a $[001]$ crystallographic face.

I suggest you study this more, namely the Langmuir adsorption model and Brunauer–Emmett–Teller Theory (BET). Especially since BET is a popular technique to measure adsorption.

  • $\begingroup$ Okay, so there is no simple way of estimating this gas is stickier than that gas provided we talk about the same absorbent,or? $\endgroup$
    – Zorg
    Commented Oct 14, 2018 at 16:14
  • $\begingroup$ @Zorg Critical point is quite useful in that sense. A least you can have some idea form the boiling point of the molecule. $\endgroup$
    – Nando
    Commented Oct 18, 2018 at 14:38

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