Question

A closed vessel contains 2 kg of carbon dioxide at temperature 20oC and pressure 0.7 bar. Heat

supplied to the vessel till the gas acquires a pressure of 1.4 bar and temperature of 313 oC.

Calculate 1. Work done on or by the gas? 3. Heat added and 4. Change in internal energy. Take

specific heat of the gas at constant volume as 0.657 kJ/kg K.​

Answer 1

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for constant volume process

P1/T1 = P2/T2

T2 = 1.4*293 / 0.7

T2 = 586 K

hence

Final temperature = 586 K

work done W = p * dV = 0

Heat added = m * Cp (T2 – T1) = 2 * 0.657 * 293 = 385 KJ

Change in internal energy U12 = Q12 – W12 = 385 – 0 = 385 KJ

hope this will help you...

-3idiots29