A steam engine goes through the following 3 step process.
I) Isobaric compression from a volume of 100 L to 10 L at a
pressure of 4 x 105 Pa
II) Isovolumetric process from a pressure of 4 x 105 Pa to a
pressure of 4 x 106 Pa at a volume of 10L.
III) An isothermal expansion from 4 x 106 Pa and a volume of 10 L
to a pressure of 4 x 105 Pa and volume of 100L, at 208 ºC
a) Using the end of step III, determine the number of moles of steam.
b) How much work is done on the gas by each step?
c) At the end of the cycle, how much heat has been added or removed from the engine?
a) Use the ideal gas law. You know P, V, and T before the expansion
n = PV/RT
n is the number of moles.
b) Use the definition of Work
Win = -Wout = - Integral of P dV.
For first step, III, P is constant so
Work in = -P*(change of V)= 4*10^5 * 90
Try doing the other steps yourself.
c)Use
Qout = Qin + Win
(Conservation of energy for a single cycle)
2 answers