PLEASE state assumptions for BOTH questions An insulated piston-cylinder device

Question

PLEASE state assumptions for BOTH questions An insulated piston-cylinder device contains 7 liters of saturated liquid water at a constant pressure of 175 kPa. Water is stirred by a paddle wheel for 45 min through a resistor placed in the water. If one-half of the liquid is evaporated during this constant-pressure process and the paddle-wheel work amounts to 400 kJ, a. Determine the work produced from the resistor. An ideal gas undergoes a sequence of mechanically reversible processes in a closed system beginning with an initial state of 70 degree C and 1 bar, which is then compressed adiabatically to 150 degree C. The second step of the sequence cools the gas from 150 to 70 degree C at constant pressure, and finally, it is expanded isothermally to its original state. You may assume 1mol of gas. calculate w, Q, delta U, and delta H for each of the three processes and for the entire cycle. Take c_v = (3/2) R and c_p = (5/2) R

Explanation / Answer

[2] Assumptions-
(1) System is considered as a closed system
(2) Electrical and paddle work both is to be considered to obtain correct answer.

[3] Assumptions-
(1) System is contained in an imaginary frictionless piston /cylinder arrangement.
   (2)The initial and final temperatures are identical, hence U = H = 0

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