JEE Main2007ChemistryThermodynamics (C)Actual
Assuming that water vapour is an ideal gas, the internal energy ( 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 373 ~K =41 ~kJ ~mol ⁻¹ and R =8.3 ~J ~mol ⁻¹ ~K ⁻¹ ) will be
Options
- A4.100 ~kJ ~mol ⁻¹
- B3.7904 ~kJ ~mol ⁻¹
- C37.904 ~kJ ~mol ⁻¹
- D41.00 ~kJ ~mol ⁻¹
Correct answer
C. 37.904 ~kJ ~mol ⁻¹
Step-by-step solution
aligned & H ₂ O ( ) vaporisation H ₂ O ( g ) & n _ g =1-0=1 & H = U + n _ g RT & U = H - n _ g RT & =41-8.3 10⁻³ 373 & =37.9 ~kJ ~mol ⁻¹ aligned Hence, (C) is correct.