Standard enthalpy of vaporisation _ vap H^ s for water at 100^ C is 40.66 ~kJ ~mol ⁻¹ . The internal energy of vaporisation of water at 100^ C (in . kJ mol ⁻¹ ) is (Assume water vapour to behave like an ideal gas).

Step-by-step solution

H ₂ O ( l ) 100^ C H ₂ O (g) _ vap H^ s = _ vap E^ s + n_g R T For the above reaction, gathered n_g=n_p-n_r=1-0=1 40.66 ~kJ ~mol ⁻¹= _ vap E^ s +1 8.314 10⁻³ 373 _ vap E^ s =40.66 ~kJ ~mol ⁻¹-3.1 ~kJ ~mol ⁻¹ =+37.56 ~kJ ~mol ⁻¹ gathered