Cleaning up exhaust gases sim
Car: the engine is drawn about 43 times slower than at idle.
Cleaning up exhaust gases · covers the GCSE, IGCSE, O-Level topic
What the sim shows
Car: the engine is drawn about 43 times slower than at idle. The particles are a picture, not a count: pollutants are drawn far more often than they really are (in real exhaust they are about 1 in 100). The flame in the cylinder passes 2000 °C, so some nitrogen and oxygen from the air join to make nitrogen monoxide; it turns into brown nitrogen dioxide only later, in the open air. The converter's numbers are this desk's estimates: warm (about 500 °C here) it converts 95% of each pollutant; it starts to work at 200 °C and works fully from 300 °C (the lesson says it works only when hot, around 300 °C); from a cold start it warms with a time constant of 60 s, and the warm-up runs 4 times faster than real time. In the converter, nitrogen dioxide is reduced by carbon monoxide (2NO₂ + 4CO → N₂ + 4CO₂), as nitrogen monoxide is; it is not simply split up. Power station: the scrubber removes 95% of the sulfur dioxide (the lesson's figure). Masses are worked by moles from the lesson's equations with O-level relative atomic masses. Each gypsum crystal in the bin stands for two SO₂ particles caught.
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