Home
Class 11
CHEMISTRY
Assuming that water vapour is an ideal g...

Assuming that water vapour is an ideal gas, the internal energy change `(DeltaU)` when 1 mole of water is vaporised at `1 ba r` pressure and` 100^(@)C, (` given`:` molar enthalpy of vaporization of water `41kJ mol^(-1)` at `1 ba r` and `373 K ` and `R=8.3 J mol^(-1)K^(-1))` will be `:`

A

`3.7904 kJ mol^(-1)`

B

`41 kJ mol^(-1)`

C

`37.904 kJ mol^(-1)`

D

`4.1 kJ mol^(-1)`

Text Solution

Verified by Experts

The correct Answer is:
C
Thermochemical equation is
`H_(2) O (1) rarr H_(2) O (g)`
Since water vapor is assumed to be an ideal gas, we have
`Delta H = Delta U + Delta n_(g) RT`
or `Detla U = Delta U = DeltaH - Delta n(g) RT`
`Delta n(g) = sum n_(p) (g) - sum n_(R) (g)`
`(1 mol) - (0 mol)`
`1 mol`
`:. Delta U = (41) - (1) (8.3 xx 10^(-3)) (373)`
`= (41) - (3.096)`
`= 37.904 kJ mol^(-1)`
Note that we need to convert `R` in kilojoules as `Delta H` is given in kilojoules.
Promotional Banner

Topper's Solved these Questions

  • THERMODYNAMICS

    R SHARMA|Exercise Ouestion Bank Level III|11 Videos

  • THERMODYNAMICS

    R SHARMA|Exercise Ouestion Bank Level IV|6 Videos

  • THERMODYNAMICS

    R SHARMA|Exercise Ouestion Bank Level I|8 Videos

  • THE S BLOCK ELEMENTS

    R SHARMA|Exercise ARCHIVES|27 Videos

Similar Questions

Explore conceptually related problems

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:

Assuming that water vapour is an ideal gas, the internal energy change (Delta U) when 1 mol of water is vapourised at 1 bar pressure and 100^(@)C , (Given: Molar enthalpy of vapourization of water at 1 bar and 373K=41 kJ mol^(-1) and R=8.3J mol^(-1)K^(-1) ) will be:

Assuming that water vapour is an ideal gas, the internal energy change (DeltaU) when 1 mol of water is vapourised at vapourisation of water at 1 bar and 373K=41 kJmol^-1 and R=8.3 Jmol^-1K^-1 will be

90 g of water spilled out from a vessel in the room on the floor. Assuming that water vapour behaving as an ideal gas, calculate the internal energy change when the spilled water undergoes complete evaporation at 100^(@)C . (Given the molar enthalpy of vaporisation of water at 1 bar and 373 K = 41 kJ mol^(-1) ).

What is DeltaU when 2.0 mole of liquid water vaporise at 100^(@)C ? The heat of vaporistaion , DeltaH vap. of water at 100^(@)C is 40.66 kJ mol^(-1) .