Question

4. Make a detailed sketch of a PV diagram showing the follo processes: Starting with 2.00 moles of helium gas at 400 K, 1.00 atm or a PV diagram showing the following three sequential 1) expand the helium isothermally from 65.6 L to 131.3 L at 400 K, 2) then cool the helium isobarically to 65.6 L, 200 K, 3) then heat the helium isochorically from 200 K back to 400 K, 1.00 atm. 15suming all the processes are carried out reversibly, compute w,q, and 4U for each step, and their net quantities around the cycle. Make sure that the net quantities obey to First Law. You will need to look up the heat capacities Cy and Cp of henum kas.

Answer 1

8 (400K, 1 atm, 65.6L) 1 att step-3 0.5 amt & Step-1 steps (400,0.5 atm, 131-32) IV 131.3L 65.6L For Step-1 (3-4) W=nRT en ve ya =-2 molx 8314 3. K! moe'x400k en! 65-6 W3 -4610-265] or Be au = nerdt, dT=0 Per 1 atm, Ve=6562 fou=o Ve = 131:32 Q = 4u-w =0-(-4610-261) ~0.5 arm Q = 4610-26) Pe = POUR = 1X65 66 For step-2 (CA) i W=- P(VA-ve) :-0.5 amm (65.6-131.3)L = 32.85 Lamm T 5 32.85X 8.314 0.082 J a= 3330.665] u= new (TA-Te) = 2x 1.5X8.314x (6 200-400) J Tu=-4988.45 . q=u-w - 4988.43 -3330.66J 9 -8319.11 J

For step-3 (A+B) :- dv=o w=opdr w=0] u=neu (TB-PA) = neu (To-TA) = 2X1,5X8-314 (400-200) uz 4988.45 q=u-w 19 = 4988.45]