Chemical Reactions in a Car Engine

a) complete combustion:

2 C8H18 (l) + 25 O2 (g) 16 CO2 (g) + 18 H2O (g)

gasoline

A tiny fraction of the gasoline doesn’t burn & is released through the car’s exhaust to the atmosphere.

Environmental Issues

CO2 & H2O are both greenhouse gases (GHG).

infrared (IR) radiation

b) formation of nitrogen oxides:

2 NO (g) + O2 (g) 2 NO2 (g)

N2 (g) + O2 (g) 2 NO (g)

Environmental Issues

1. Nitrogen oxides are a component of smog.

2. Nitrogen oxides react with sunlight & unburned gasoline to form ground level ozone.

Ground level ozone causes:

cracked tires & windshield wipers

respiratory distress

3. Nitrogen oxides also contribute to the formation of acid rain.

Treating Car Exhaust

catalytic converter

A catalytic converter will:

decompose nitrogen oxides:

change the unburned gasoline into carbon dioxide & water

2 NO2 (g) N2 (g) + 2 O2 (g)

How Do Catalytic Converters Work?

Catalytic converters contain precious metals such asplatinum, palladium, & rhodiumthat act as catalysts.

A catalyst is a substance that makes a reaction happen faster without being used up in the reaction.