Question

Calculate the number of pounds of CO2 released into the atmosphere when a 21.0-gallon tank of gasoline is burned in an automobile engine. Assume that gasoline is primarily octane, C8H18, and that the density of gasoline is 0.692 g·mL–1 (this assumption ignores additives). Also assume complete combustion.

Answer 1

we know that

1 gallon = 3785.41 ml

so

volume of gasoline = 21 x 3785.41

volume of gasoline = 79493.61 ml

now

we know that

mass = density x volume

so

mass of gasoline = 0.692 x 79493.61

mass of gasoline = 55009.578 g

now

we know that

moles = mass / molar mass

also

molar mass of C8H18 = 114

so

moles of C8H18 = 55009.578 / 114 = 482.54

now

the combustion reaction is

C8H18 + excess 02 ---> 8 C02 + 9H20

we can see that

moles of C02 = 8 x moles of C8H18

so

moles of C02 = 8 x 482.54 = 3860.32

now

mass = moles x molar mass

so

mass of C02 = 3860.32 x 44 = 169854 g

we know that

1 g = 0.00220462 pound

so

mass of C02 = 169854 x 0.0020462 = 374.464

so

374.464 pounds of C02 is produced