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One moles of an ideal gas which C(V) = 3...

One moles of an ideal gas which `C_(V) = 3//2 R` is heated at a constant pressure of `1 atm` from `25^(@)C` to `100^(@)C`. Calculate `DeltaU, DeltaH` and the entropy change during the process.

Text Solution

Verified by Experts

As `(C_(P) - C_(v)) = R rArr C_(p)=C_(v) + R`
`rArr C_(p) = 3/2 R + R= 5/2 R`
Heat given at constant pressure.
`(DeltaH) = nC_(p)DeltaT = 1 x 5/2 R xx (373 - 298)`
`rArr (DeltaH) = 1 xx 5/2 xx 1.987 xx 75 = 372.56` cal
Work done in the process = `-PDeltaV`
`=-P(V_(2)-V_(1))`
`=-P((nRT_(2))/P -(nRT_(1))/P)` (As PV = nRT)
`=-nR(T_(2)-T_(1))`
`=-1 xx 1.987 xx (373 - 298)`
`=-149.05` cal.
From first law of thermodynamics.
`DeltaE = q+W`
`=372.56 - 149.05`
=223.51 cal.
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