1.

What is the value of change in internal energy at 1 at, in the process H_(2)O (l, 323 K) rarr H_(2)O (g, 473 K) Given : C_(p) (H_(2)O, l)=75.3 JK^(-1) mol^(-1) , C_(p) (H_(2)O, g)=33.314 JK^(-1) mol^(-1), DeltaH_(vap) at 373 K=40.7 kJ//mol

Answer»

`109.1 kJ//mol`
`37.6 KJ//mol`
`43.86 KJ//mol`
`48.36 KJ//mol`

Solution :`H_(2)O (L, 323 K) rarr H_(2)O (G, 473 K)`
`H_(2)O (l, 323 K) overset(Delta_(r) U_(1))(rarr) H_(2)O (l, 373) overset(Delta_(r)U_(2))(rarr) underset(("for solid and liquid "C_(P)~~C_(V))(H_(2)O (g, 373) overset(Delta_(r)U_(3))(rarr) H_(2)O (g, 473))`
and `""Delta_(r)U=Delta_(r)U_(1)+Delta_(r)U_(2)+Delta_(r)U_(3)`
`=C_(V, m)DeltaT+(Delta_(r)H_(2)-Deltan_(g)RT)+C_(V, m)DeltaT`
`=(75.3xx50)/1000+(40.7-(1xx8.314xx398)/1000)+((33.314-8.314)xx100)/1000`
`Delta_(r)U ~~43.86" kJ/mol"`


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