1.

One mole of an ideal gas (C_(v) = 3/2R) is heated at constant pressure of 1 atmosphere from 25^(@) C to 100^(@) C. Calculate DeltaE and DeltaH.

Answer»

Solution :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.


Discussion

No Comment Found

Related InterviewSolutions