In a steam engine, steam in a cylinder expands against a piston, exerting 10 atm of external pressure. The volume of the cylinder increases by 10 L and simultaneously the steam cools, losing 3,000 kJ of energy to the surroundings. What is the change in energy of the steam?
(101.3 J = 1 L atm)

Question

Quizplus · Accepted Answer

The change in energy of the steam is equal to the work done by the steam against the external pressure minus the heat lost to the surroundings. The work done by the steam is given by:W = PΔV = (10 atm)(10 L) = 100 L atmConverting to kJ using the conversion factor given in the question:W = 100 L atm * (101.3 J / 1 L atm) = 10,130 J = 10.13 kJThe change in energy of the steam is then:ΔE = W - Q = 10.13 kJ - 3,000 kJ = -2,990 kJTherefore, the correct answer is E.

In a Steam Engine, Steam in a Cylinder Expands Against