In: Chemistry
A large SUV has a mass of 2400 kg .
Calculate the mass of CO2 emitted into the atmosphere upon accelerating the SUV from 0.0 to 65.0 mph . Assume that the required energy comes from the combustion of octane (ΔH∘f=−250.1 kJ) with 30% efficiency. (Hint: Use KE=12mv2 to calculate the kinetic energy required for the acceleration.)
Kinetic energy of vehicle = 1/2 mv2
velocity of vehicle in si unit = 29 m/s
K.E = 1/2 x 2400 x 292 = 1009200 J = 1009.2 kJ
Combustion of octane equation
2 C8H18+ 25 O2 ---> 16 CO2 +18 H2O
We have enthalpy of formation of octane
Enthalpy of above reaction = enthalpy of products - enthalpy of reactants = 16 x -393.5 +(18 x -285) - { -250.1 x2}
= 10925 kJ
It produces 16 mol carbon dioxide
To produce 1009.2 kJ at 30% efficiency we have to use
10925 kJ x n x 30/100 = 1009.2 kJ
n = no. Times 16 mol CO2 produced to achieve the required amount of energy
n = 0.308 x 16 = 4.93 mol
Mass of carbon dioxide = 4.93 x 44g/mol = 216.77g