[jcompton]

In order to grow MWCNTs I need to have certain content of water vapor
dissolved in the argon gas. The amount of water vapor can be changed with
temperature of the water that argon bubbles through. I have Argon entering a flask with water in it. The flow of the argon is 120 ml per min. It makes bubbles about 3 mm in
diameter and travels about 2 cm through the water in the flask. The bubble
is in contact with water for about 0.2s. How would I go about estimating how
much water vapor can mix with the dry argon gas when the temperature is 20C?

[Borek]

Sounds more like engineering question (ie engineers have methods to estimate similar things). But could be you will not find anything, these are not simple questions.

[typhoon2028]

Is this a problem you have to calculate the answer to, like for homework?  Or can you do some lab tests?

This seems like a mass transfer problem.  I have not done a mass transfer problem in a long time.

However, most of the water mixing in the vapor phase probably can be attributed to vapor pressure alone.  If you could measure the total water loss over time in your flask, then subtract out what water would be loss by vapor pressure.

If total water loss (experimentally) - vapor pressure = positive number (small number) <-- mass transfer of water/argon stripping
If total water loss - vapor pressure = large number <-- probably more investigation into mass transfer theory

I am assuming 120 mL/min of argon is enough argon gas to displace air from the the top of your flask.