1.

10 g of neon initinally at a pressure of 506.625 kPa and temperature of 473 K expandadiabaticallyto a pressure of 202.65 kPa .Calculateentropyofthe system and oftotalentropy changefor the following waysof carryingout is this expamsion .(i) Expansion is carriedout expansion . (ii) Expansionoccursaganista constant external pressureof 202.65 kPa . (iii) Expansion is a free expansion.

Answer»


Solution :(i)For reversibleadiabaticprocess
`DeltaS_(surr)= 0""DeltaS_(sure)= - DeltaS_(SYSTEM) = 0`
`DeltaS_("total") = DeltaS _(SYS)+DeltaS = 0 `
Hence `DeltaS_(sys)= DeltaS_(surr)= DeltaS_("total") =0`
(ii)`DeltaS_(surr)= 0`
`DeltaS_(sys)= nC_(V)In ((T_(2))/(T_(1)))+ nR In ((V_(2))/(V_(1)))`
`= nC_(V) In ((T_(2))/(T_(1))) + nR In ((P_(1))/(P_(2))(T_(1))/(T_(2)))`
`= N[C_(V) In ((T_(2))/(T_(1))) + nR In ((T_(2))/(T_(1)))+ In((P_(1))/(P_(2)))]`
`= n[C_(V) In ((T_(2))/(T_(1))) + nR In((P_(1))/(P_(2)))]""[T_(2)" of irreverrsubile adiabatic will be calculated "]`
`= 0.957 J//K""byw = DeltaU rArr - P_(ext)(V_(2)-V_(1))=nC_(V,m)(T_(1)-T_(2))`


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