# How to convert permeation units to molecules/second?

How do I convert $\dfrac{\text{cm}^3\cdot\text{mm}}{\text{m}^2 \cdot \text{day} \cdot \text{atm}}$ for permeation of gas through EVOH to molecules of gas permeating per second as a function of thickness of EVOH?

In other words, I am trying to use the permeation units to determine how much a container will be emptied of gas via permeation after a given amount of time.

• Is that supposed to be $\dfrac{\text{cm}^3\text{mm}}{\text{m}^2}\text{d}\cdot \text{atm}$ or $\dfrac{\text{cm}^3 \text{mm}}{\text{m}^2 \cdot \text{d} \cdot \text{atm}}$? Also, $\text{d}$ isn't a unit. – Wasabi Aug 14 '16 at 2:15
• @Wasabi It is the latter form of the two that you have suggested. I have given the data as it was given on the material publication. D is short for day. Here is a link to a company that makes EVOH and provides some detail with regard to permeation. Look at page 7. Under OTR (oxygen transmission rate) there are units for permeation. evalevoh.com/media/124484/eval_resins_and_film_emea.pdf – Hypnos Stratagem Aug 14 '16 at 3:45
• You might want to review how Avagadro's Number can be used to convert volume of a gas to the number of molecules in a gas. I suspect the conversion will be vary for different gases. – Fred Aug 14 '16 at 15:24