QUESTION $2[15$ MARKS$]$

An insulated piston$-$cylinder device contains $5L$ of saturated liquid water at a constant

pressure of $175$kPa. Water is stirred by a paddle wheel while a current of $8$A flows for $45$

min through a resistor placed in the water. If $50\%$ of the liquid is evaporated during this

constant$-$pressure process and the paddle$-$wheel work amounts to $400kJ.$

a$)$ Visualize the process on a $Pv-$diagram with respect to the saturation line.

$[2$ Marks$]$

$[$CO$2,$ PO$2,$ C$2,$ SP$1]$

b$)$ Demonstrate that for a closed system, the works of the system and the change in internal

energy in the first$-$law relation can be combined into one term, $H,$ for a constant

pressure process.

$[3$ Marks$]$

$[$CO$2,$ PO$2,$ C$2,$ SP$1]$

c$)$ Determine the voltage of the source.

$[10$ Marks$]$

$[$CO$2,$ PO$2,$ C$2,$ SP$3]$