Question

Now let's do the same type problem only starting with 11 gallons of gasoline (a typical tank of gas) and asking how many kilograms of CO₂ are produced?

First, get 11 gallons of gasoline into grams. You need a couple of conversion factors here. 1 gallon is 3.8 Liters. The density of gasoline is 720 g/L.

Next, convert to moles from grams. Here you need to know the formula of octane, C₈H₁₈, in order to calculate the molar mass. So how many moles of gasoline (octane) are in 31000 grams of gasoline?

Using the balanced equation from the combustion of octane, how many moles of CO₂ are produced from 270 moles of octane?

Using the molar mass of CO₂, calculate the number of grams of CO₂ produced by that number of moles. Let's use 2200 moles.

Finally, you convert to the desired units, in this case kg where 1 kg is 1000 g. Let's use 93000 g as our amount of CO₂? [By the way, you should notice that the amount of CO2 produced is roughly 3x the amount of hydrocarbon fuel that we started with. Why? The hydrocarbon fuel produces one CO₂ for each carbon in the fuel. Each C combines with two additional, nearly equal in weight, oxygen atoms. If you ever need to guess the answer to this type of question that's a good rule of thumb.]

Answer 1