The combustion of one mole of liquid octane, \(\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{6} \mathrm{CH}_{3}\), produces 5470 kJ of heat. Calculate how much heat is produced if 1.000 gallon of octane is combusted. See Exercise 3.68 for necessary information about octane.
Text Transcription:
CH3(CH2)6CH3
Step 1 of 5) The combustion of one mole of liquid octane, , produces 5470 kJ of heat. Calculate how much heat is produced if 1.000 gallon of octane is combusted. See Exercise 3.68 for necessary information about octane.Some thermodynamic quantities, such as E, are state functions. Other quantities, such as q and w, are not. This means that, although ∆E = q + w does not depend on how the change occurs, the specific amounts of heat and work depend on the way in which the change occurs. Thus, if changing the path by which a system goes from an initial state to a final state increases the value of q, that path change will also decrease the value of w by exactly the same amount. The result is that ∆E is the same for the two paths. We can illustrate this principle using a flashlight battery as our system. As the battery is discharged, its internal energy decreases as the energy stored in the battery is released to the surroundings. In Figure 5.10, we consider two possible ways of discharging the battery at constant temperature. In Figure 5.10(a), a wire shorts out the battery and no work is accomplished because nothing is moved against a force. All the energy lost from the battery is in the form of heat. (The wire gets warmer and releases heat to the surroundings.) In Figure 5.10(b), the battery is used to make a motor turn and the discharge produces work. Some heat is released, but not as much as when the battery is shorted out. We see that the magnitudes of q and w must be different for these two cases. If the initial and final states of the battery are identical in the two cas
