Please Help! Your car has 1.95 gallons of gasoline (octane, d = 0.6916 g/mL), which reacts with oxygen
according to the balanced reaction below. Your car uses the energy produced by this reaction
at a rate of 115 kJ per second while traveling at a speed of 65 miles per hour. Calculate the
distance (in miles) the car can travel using this amount of octane.
2 C8H18(g) + 25 O2(g) > 16 CO2(g) + 18 H2O(g) ΔHrxn = -10,900 kJ

38.3 miles

Explanation:

First, we convert 1.95 gallons to mililiters:

Then we calculate how many grams of octane are available for the reaction, using its density:

Now we convert octane grams into octane moles, using its molar mass:

Then we calculate how many kJ are produced from the combustion of  44.78 mol C₈H₁₈, if 2 moles produce 10900 kJ:

We calculate how many seconds is the car available to keep going, if it spends 115 kJ per second:

We convert seconds to hours:

Finally we calculate the distance: