Hexane is throttled from 18.15 bar, 507.6 K to 0.1 bar.  Determine the temperature at the exit and the entropy generation.

Steam is cooled under constant pressure from 400^oC, 3 bar to a final state that contains wet steam with Xv = 0.9.  (hint: for this problem it might be easier to use the Mollier diagram than the steam tables)

a.  Determine ?H and ?S.

b.  Determine the heat needed to increase X_v to 1.

3.  A tank (V = 0.19 m³ ) full of cyclohexane and T = 554 K explodes at P = 20 bar.  The final state of cyclohexane is a vapor at 1 bar.

a.  What is the final temperature of the cyclohexane?  The ideal gas, constant pressure heat capacity of cylcohexane is 200 J/mol/K.

How much energy was released in the explosion?

4.  An insulated tank at 20 bar contains wet steam with 20% moisture.  The tank is emptied by throttling its contents to the atmosphere, assumed to be at 1 bar.  Assuming the entropy generation inside the tank is zero and the initial specific entropy inside the tank is Si, what is the entropy of the tank (in J/K) when it is half empty by mass?