Question

Calculate the photostationary-state mixing ratio of ozone when pd = 1013 mb, T = 298 K, J = 0.01 s⁻¹, k1, = 1.8 X 10⁻¹⁴ cm molecule⁻¹ 's⁻¹, XNO(g) = 180 ppbv, and XNO₂ (g) 76 ppby. Perform the same calculation under the same conditions, except, XNO(g) = 9 ppby and XnO2(g) = 37 ppbv.

(a) Ignoring the constant temperature and photolysis coefficient, which of the two cases do you think represents afternoon conditions? Why?

Answer 1

The photostationary-state mixing ratio of ozone is determined by the equilibrium between NO, NO2, and O3. The provided mixing ratios, photolysis rate, and reaction rate constant are critical factors in this calculation. The scenario with higher NO concentration likely represents afternoon atmospheric conditions.

Step-by-step explanation:

To calculate the photostationary-state mixing ratio of ozone, we need to understand how NO, NO2, and O3 interact in the atmosphere. The equilibrium between these species is represented by the following reactions:

1. NO(g) + O3(g) → NO2(g) + O2(g)
2. NO2(g) + sunlight → NO(g) + O(g)
3. O(g) + O2(g) → O3(g)

The mixing ratios provided in the question represent the initial concentrations of the species involved. The photolysis rate (J) and the reaction rate constant (k1) are also important in predicting the ozone mixing ratio.

In the given scenarios, a higher level of NO suggests more vehicular emissions and industrial activities, which are typically higher during the afternoon. Therefore, the scenario with the higher NO concentration (180 ppbv) likely represents afternoon conditions.