Question

3 moles of ideal gas is heated as constant pressure from 27 degree cantegrate to 127 degree centigrade.

(a) Find the workdone for the expansion of gas?

(b) If the gas were expanded isothermally in a irreversible manner at 27 degree centigrade from 1 atmosphere to 0.7 atmosphere. Calculate the workdone.

Answer 1

a.

T initial = 27 0C =300K

T final = 127 0C = 400K

V initial = nRTinitial /P

V final = nRT final /P

W= -PV=- p(V final – V initial ) = -(P nR/p)*( T final – T initial )

= - 3 x 8.314 x ( 400-300)=-2494.2 J

b.

T= 27 0C

For isothermally

iriversibly

w= -2.303 nRT log (P(1)/P(2))=-2.303 x 3 x 8.314 x 300 x log(1/.7)= 2669.303 J