# Question: assume that the air over a city behaves as a...

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Assume that the air over a city behaves as a well-mixed control volume. The area of the city is 100 km × 100 km, and the control volume extends 800 m above ground level. Clean air blows into the box from the west at a speed of 4 m/s. A power plant emits nitrogen dioxide into the control volume at a rate of 80 kg/s. Nitrogen dioxide is degraded in the lower atmosphere via a first-order reaction with rate constant, k, of 0.15 hour-1. Find the steady-state concentration of nitrogen dioxide in the city’s air. Report your answer in ppm.