The permitted CO emission level for new cars in California a

The permitted CO emission level for new cars in California and the Northeast is 2.1 g/mi. Assume that the fuel economy is 25 mi/gal and the density of gasoline is 0.72 kg/L.
a. Calculate the CO emission factor for automobiles in lb CO/ton of fuel burned.
b. Assuming complete combustion, calculate the corresponding CO₂ emission factor for automobiles in lb CO₂/ton of fuel burned. (The composition of gasoline may be approximated as octane, C₈H₁₈).

Solution

a.

The permitted CO emission level = 2.1 g/mi

Fuel economy = 25mi/gal

So, the permitted emission level per gal = 25 x 2.1 g/gal = 52.5 grams of CO/gallon of fuel burnt

In terms of g/litres, it will be 52.5/3.785 = 13.87 grams of CO/litre of fuel burnt

Now, since the density of gasoline is 0.72 kg/l or 720g/litre

Therefore, the emission level will become 13.87/720 = 0.0193 grams of CO/gram of fuel burnt

For 1 ton(1000kgs) of fuel burnt, CO produced = 0.0193 x 1000 x 1000 grams = 19300 grams = 19300/454 = 42.511 lbs.

Therefore, CO emission factor will be 42.511 lbs/ ton of fuel burnt

2.

For complete combustion of Gasoline, the chemical reaction is given as;

C₈H₁₈ + 12.5O₂ = 8CO₂ + 9H₂O

i.e. 1 mole of Gasoline will produce 8 moles of Carbon Dioxide

or, 114 grams (12x8 + 1x18) of Gasoline will produce 352 grams (8 x (12+32)) of CO2.

1 tonne of fuel (Gasoline) burnt will produce 1000000 x 352/114 = 3087719 grams of CO2 = 3087719/454 = 6801 lbs of CO2

Therefore, the CO2 emission factor will be 6801 lb CO₂/ton of fuel burnt.