Questions

2.15 Entropy - A Basic Understanding

1 What is true of entropy?
a) It is not a physical property of steam
b) It reflects the quality of energy during a process
c) It is energy change divided by the mean temperature of the change
d) It is all of the above
2 From the Mollier diagram in Figure 2.15.8, if the initial state point was saturated steam at 2 bar, the final state point was at 0.01 bar, and the expansion was isentropic, what is the approximate heat drop in one kilogram of steam?
a) 2000 kJ
b) 2700 kJ
c) 700 kJ
d) 1000 kJ
3 What always accompanies an isentropic expansion of steam?
a) An increase in entropy
b) An increase in enthalpy
c) A decrease in entropy
d) A decrease in enthalpy
4 What always accompanies an isenthalpic expansion of steam?
a) An increase in entropy
b) An increase in enthalpy
c) A decrease in entropy
d) A decrease in enthalpy
5 What is true about steam as it condenses?
a) It does so at constant entropy and temperature
b) It does so at constant enthalpy and reducing temperature
c) Both enthalpy and entropy reduce and temperature remains constant
d) Both enthalpy and entropy increase
6 From the Mollier diagram in Figure 2.15.8, if the initial state point was saturated steam at 2 bar, the final state point was at 0.01 bar, and the expansion was isenthalpic, what is the approximate heat drop in one kilogram of steam?
a) None
b) 1.5 kJ
c) 700 kJ
d) 2 000 kJ