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A swimmer coming out from a pool is cove...

A swimmer coming out from a pool is covered with a film of water weighing about 18g. How much heat must be supplied to evaporate this water at 298 K? Calculate the internal energy of vaporisation at `100^@C`. `DeltaH_(vap)^@` for water at `373K = 40.66 kJ mol^(-1)`

Text Solution

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We can represent the process of evaporation as
` H _(2) O _((l)) overset("vaporisation ")to H _(2) O_((g)), Delta n =1 - 0 =1`
`Delta _(vap) E = Delta _(vap) H - r Delta V =Delta _(vap) H - Delta n RT`
(assuming steam behaving as an ideal gas).
`Delta _(vap) E = 40.66 kJ mol ^(-1) -(1)`
`( 8.314 xx 10 ^(-3) KJK ^(-1) mol ^(-1)) (375 K) = 37.56kJ mol ^(-1)`
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