Question

Because (∂H/∂P)T =−CPμJ−T, the change in enthalpy of a gas expanded at constant temperature can be calculated. To do so, the functional dependence of μJ−T on P must be known.

Part A Treating Ar as a van der Waals gas, calculate ΔH when 1 mole of Ar is expanded from 329 bar to 1.68 bar at 375 K. Assume that μJ−T is independent of pressure and is given by μJ−T=[(2a/RT)−b]/CP,m, and CP,m=5/2R for Ar. The van der Waals parameters a and b for Ar are 1.355 bar⋅dm6⋅mol−2 and 0.0320 dm3⋅mol−1, respectively.

Part B What value would ΔH have if the gas exhibited ideal gas behavior?

Answer 1

SadluCion According to uen that catavtate Ap bthe fommla a fottowg AP Pa-P Subaltute 68 bafo P 329 ban fon P n the eq) a 68 ban - 329 baa AP - 327 .32 baa Calculate the value of -1 by the foamula a follouws Subttute 355 bandm ba mo a) o.0320dm3 molfon b 315 K fon t and 8314 Iombax moifon R n the equalon ( foos baa mo 2x.355 dm O 0320m tme x 315 k 8.314 102 dm3 ban iomoi .0S9 dmmo P,m

O.055d m3 moi fo mol value af -T a foiloog Aathe 0.055 dm3 moi mo P,m 0 O55 dm3 Conveat the v alue aom dm to L by the conveasfon factor follows: 1dm1L L 0.055 dm3 x O.055 dm dm3 O.055L Calculate he value py)P) Bvotute 0.055L ard 32. 32 baaaP P,m the equation (3) afoltows O OS5 L ४ (-3२- .3२ ba) Att CP, m 18,0026 Lba

O.055d m3 moi fo mol value af -T a foiloog Aathe 0.055 dm3 moi mo P,m 0 O55 dm3 Conveat the v alue aom dm to L by the conveasfon factor follows: 1dm1L L 0.055 dm3 x O.055 dm dm3 O.055L Calculate he value py)P) Bvotute 0.055L ard 32. 32 baaaP P,m the equation (3) afoltows O OS5 L ४ (-3२- .3२ ba) Att CP, m 18,0026 Lba

Convet to 3by the Convea son fac-toa L bax IL banlooJ 18.0026 tbax 18. o026 baa x Lba 80026 X10 AH .80026 x10T The value of AH is 80026 x io3J vatue of ij-T Tthe gas s dealthen the The value of Att so