posted by Donna .
Which odor will be detected first if both containers are opened simultaneously, NH3 or H2S vapors?
I assume the person making up this problem expects us to answer based on the rate of effusion of H2S vs NH3 and NH3 wins in that case. However, I don't think it's as simple as that. It depends upon the individual, their sensitivity to H2S vs NH3, air currents, as well as the senses of the olfactory nerves of the nose to H2S vs NH3. For example, it doesn't take very much H2S in the air to detect it. The detection limit for H2S in air by the nose is about 0.03 ppm and for NH3 it is about 3 ppm--quite a difference and 100 times less for H2S. From that I would expect H2S to be the first to reach the nose.