If you mean that you want the vapour to be 100ppm.

Vapour pressure of ammonia (at 21oC): 8.76atm

PV=nRT

P=n/V*RT

P/R/T=[NH3]

8.76/8.314/(273.15+21)=[NH3]

0.00358M=[NH3]

This is the concentration of ammonia in its vapour form above pure ammonia. In ppm it is 60.97 (0.00358mol/L*17.031g/mol*1000mg/g).

Hmm.... is that even possible?

Dear Subhrajit,

Since it is a solution in water, you need to take this into account and calculate the partial pressure at the applied temperature and I assume at atmospheric pressure. I think this document I found online might be helpful, especially tables 9 and 10.

Kind regards,

Katrijn

Thank you Katrijn, your document help me a lot.

Calculate the amount of ammonia in your solution (consider pH). then get the Henry constant (about 60 m/atm) and calculate the partial pressure. http://en.wikipedia.org/wiki/Henry's_law

I have tried this. Biggest problem is accounting for water response.