Reaction of N2O5 with H2O on bulk liquids and on particles and the effect of dissolved HNO3

Measurements of the reaction probability (γ) of N2O5 on ∼60 wt% H2SO4 were performed at 201 to 230 K on bulk liquids and at 230 K on aerosol particles. The bulk and aerosol results are in good agreement (less than 10% difference). The measurements on bulk liquids show very little change in γ with temperature from 201 to 230 K. HNO3 was added to the bulk liquids at ∼201 K and to aerosol particles at 230 K (the H2SO4‐content was decreased to keep water activity approximately constant). For [HNO3] levels of 1‐to‐15 wt %, the N2O5 reaction probability decreased by ∼15% from that measured on HNO3‐free 60 wt% H2SO4. For 60 wt% H2SO4 aerosol in the stratosphere ([HNO3] ∼0.3 wt%) the decrease in the N2O5 hydrolysis reaction probability due to HNO3 would be small.