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The volume of 1 kg of hellum in a piston-cylinder device is initially 5 m3. Now

ID: 1771808 • Letter: T

Question

The volume of 1 kg of hellum in a piston-cylinder device is initially 5 m3. Now hellum is compressed to 2 m3 while Its pressure is maintained constant at 170 kPa. Determine the initial and final temperatures of helum as well as the work required to compress it, in kJ. The gas constant of helium is given to be R 2.0769 kJ/kg K (Round the temperatures to one decimal place and the work required to the nearest whole number. he ini t of hlum K. K. The final temperature of helium is The work required to compress the hellum is KJ.

Explanation / Answer

Work done to compress gas= - P ( change in volume) ( isobaric process
W= - (170 x 10^3 ) (2 -5) = 510 x 10^3 J or 510 KJ

number of moles in 1 kg of helium=249.837

PV = nRT

170 x 10^3 ( 5) = 249.837 (8.314) ( Tinitial)

T = 409 . 215 K

T final =( 170 x 2 x 10^3)/  249.837 (8.314) = 163.686 K