Question

The change in internal energy for the combustion of 1.0 molmol of octane at a pressure of 1.0 atmatm is -5084.1 kJkJ . Part A If the change in enthalpy is -5074.4 kJkJ , how much work is done during the combustion

Answer 1

Answer:

W = -10.3 kJ

Explanation:

During combustion, the system performs work and releases heat. Therefore, the change in internal energy is negative, and the change in enthalpy, which is equal to heat at constant pressure, is also negative. Work is then calculated by rearranging the equation for the change in internal energy:

w=ΔE−qp=−5084.3 kJ−(−5074.0 kJ)

The release of heat is much greater than the work performed by the system on its surroundings. The potential energy stored in the bonds of octane explains why considerably large amounts of energy can be lost by the system during combustion.