Question

How is nitrogen dioxide formed in a car engine?

Answer 1

Most of the fuels and oil that are used in motor vehicles and in the car engine consist of nitrogen and its compounds.

When a vehicle or a car is running, the engine gets heated up to very high temperatures. At such very high temperatures, this nitrogen reacts with the oxygen from the atmosphere to form nitrogen based oxides like Nitrogen monoxide (NO).

N₂ + O₂ → 2NO

This Nitrogen monoxide when released from the exhaust systems of the vehicles or cars, combines with the oxygen from the air and forms Nitrogen dioxide.

2NO + O₂ → 2NO₂

This released NO and NO₂ are together called as NOₓ. These gases tend to cause irritation to the lungs, cause breathing problems, worsen asthma, and cause acid rain.

Answer 2

When fuel is burned in a car engine, the high temperature is reached.  At this high temperature, nitrogen, and oxygen from the air combine to produce nitrogen monoxide.
When this nitrogen monoxide is released from vehicle exhaust systems, it combines with oxygen in the air to form nitrogen dioxide.
Nitrogen dioxide causes acid rain. It also causes breathing problems and worsens asthma.Hope this will prove helpful.