Question

A large sport utility vehicle has a mass of 2.6 103 kg. Calculate the mass of CO2 emitted into the atmosphere upon accelerating the SUV from 0.0 mph to 54.4 mph. Assume that the required energy comes from the combustion of octane with 20.0% efficiency. (Hint: Use KE = ½mv2 to calculate the kinetic energy required for the acceleration. ΔHrxn = -5074.1 kJ.)

Answer 1

54.4 mph = 87.55 Kmph = 24.32 m/s

Kinetic energy acquired by the vehicle = 1/2 mV² - 0 = 1/2 * 2600 * 24.32² = 768.9 kJ

Now to get 768.9 kJ from the reaction, we need to burn 768.9/5041.1 kJ of octane = 0.1525

Now since efficiency is 20% we will have to compensate for the low values of efficiency by burning 0.1525 / 0.2 = 0.762 moles of octane. Burning 1 mole octane releases 8 mole CO₂. So 0.762 moles octane will yield 6.101 moles CO₂.

Mass of CO2 emitted, will be 44*6.101 = 268.44 g