Nitric Acid-Air Diffusion Coefficient: Experimental Determination Using a Diffusion Cell

Trace gaseous nitric acid was generated using a diffusion cell. The determination was made by collection in cellulose filters coated with K2CO3 and measuring the concentration by ion chromatography. The measured HNO3-air diffusion coefficient was 0.0404±0.0010 cm2/s (n=21) for T=298.15 K and P=1 atm. Their dependence with the temperature, over the range from 297.15 K to 318.15 K, could be expressed by D = 10−4.7773.T1.366 (R2=0.9467).