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1) Find the pressure (in atm) at point C in atmospheres atm. P c = _____________

ID: 2256227 • Letter: 1

Question

1)       Find the pressure (in atm) at point C in atmospheres atm.       

  Pc = _____________ atm

2)       Find the heat (in J) exhausted in the process B to C .       

  Q = __________________ J

3)       If  the net work done by the engine per cycle is 482.9 J, find the       work done by the gas during process C to A.       

  WCA = ________________ J

A heat engine has the three step cycle shown above. Starting from point A, 1 L (liter) of monatomic ideal gas expands in the isobaric (constant pressure) process A to B at P = 2 atm. B to C is isovolumetric process at V = 5 L, and C to A is an isothermal (constant temperature) compression at 300 K. Find the pressure (in atm) at point C in atmospheres atm. Find the heat (in J) exhausted in the process B to C . If the net work done by the engine per cycle is 482.9 J, find the work done by the gas during process C to A.

Explanation / Answer

1)

Pa*Va=Pc*Vc

2*1=Pc*5

Pc = 0.4 atm

2)

heat (in J) exhausted in the process B to C .

q =(Tb-Tc)*(3/2)*R

Va / Ta = Vb / Tb

Tb = Va * Ta / Vb

Tb = 5 * 300 / 1

Tb = 1500

q = 1.5*R*1200

q = 1.5*8.314*1200 = 14.9652 kj

3)

Wab = 2atm(5-1) = 8 atm-liter = 810.6 J

Wnet = Wab - Wac

Wac = 810.6 - 482.9 = 327.7 J