Calculate the energy in MegaJoules (MJ) (a) 1 liter (approximately 1 quart) of o

Question

Calculate the energy in MegaJoules (MJ)

(a) 1 liter (approximately 1 quart) of octane, a primary component of gasoline. In this case, the chemical energy is released by burning. Octane has a heat of combustion of 5.07 x 103 kJ/mole, a density of 0.703 g/cm3, and a molecular weight of 114 g/mole.

b) A car with mass of 1500 kg (about 3300 pounds) traveling at a velocity of 100 km/hour (about 60 miles per hour). In this case, the energy is in the form of kinetic energy, calculated as (1/2)mv2, where m is the mass and v is the velocity.

c) A person with mass of 75 kg at the top of a cliff of height 100 meters (over 300 feet). In this case the energy is potential energy, given by the formula mgh, where m is mass, g is the gravitational acceleration constant of 9.8 m/sec2, and h is the height.

d) A 12 Volt lead acid car battery that has mass of 10 kg (just over 20 pounds). From data on battery electrical energy storage density, the energy storage capacity of a battery of this type is 0.17 MJ/kg.

Explanation / Answer

a. delta H = heat x density x volume / molecular mass

= 5.07*103 kj/mole * 0.703 g/cm3 *1000 cm3 / 114 g/mole = 31265 kJ

= 31.296 MJ

      b.   J = kg* m2/ s2      1000 km/h = 1000000 m/ (60*60) s = 277.77 m/s

              E =

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