How do you convert ppm (in air) to molarity?

I was given a list of threshold concentrations for certain chemicals to activate a nerve. These threshold concentrations were given as ppm (stimulus administered in air). I am trying to convert these values into molarity so that I can compare these values to new recorded values and activation curves (where the... show more I was given a list of threshold concentrations for certain chemicals to activate a nerve. These threshold concentrations were given as ppm (stimulus administered in air). I am trying to convert these values into molarity so that I can compare these values to new recorded values and activation curves (where the stimulus was applied as a liquid). Anybody know how to convert ppm (in air) to molarity?
3 answers 3