posted by jer .
suppose a car operates so inefficently that only 16% of the thermal energy from burning fuel is converted to useful "wheel turning" (mechanical energy) how many kj of useful energy would be stored in a 20 gallon tank of gasoline?(assume that octane burning and gas burning produce the same results)
Write the equation for octane + O2 ==> CO2 +_ H2O and balance it.
Convert 20 gallons octane to L, then use the density of octane to convert to grams.
Look up the combustion energy for octane and convert to grams octane you have in the 20 gallons, multiply by 16% to arrive at the energy stored.
i don now