Assuming that water vapour is an ideal gas, the internal energy change `(DeltaU)` when 1 mole of water is vaporised at 1 bar pressure and `100^(@)C` , (given: molar enthalpy of vaporisation of water `-41KJmol^(-1)` at 1 bar and `373K` and `R=8.3Jmol^(-1)Kmol^(-1)`) will be:A. `4.100KJmol^(-1)`B. `3.7904KJmol^(-1)`C. `37.904KJmol^(-1)`D. `41.00KJmol^(-1)`

Assuming that water vapour is an ideal gas, the internal energy change

1.	Assuming that water vapour is an ideal gas, the internal energy change `(DeltaU)` when 1 mole of water is vaporised at 1 bar pressure and `100^(@)C` , (given: molar enthalpy of vaporisation of water `-41KJmol^(-1)` at 1 bar and `373K` and `R=8.3Jmol^(-1)Kmol^(-1)`) will be:A. `4.100KJmol^(-1)`B. `3.7904KJmol^(-1)`C. `37.904KJmol^(-1)`D. `41.00KJmol^(-1)`
Answer» Correct Answer - B `H_(2)O_((l))overset(vap o risation)(rarr)H_(2)O_((g))` `Deltan_(g)=1-0=1` `DeltaH=DeltaU+Deltah_(g)RT` `DeltaU=DeltaH-Deltan_(g)RT` `=41-8.3xx10^(-3)xx373=37.9KJmol^(-1)`

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