Question

If water vapour is assumed to be a perfect gas, molar enthalpy change for vaporisation of 1 mol of water at 1 bar and 100degree Celsius is 41kj mol^-1. calculate the internal energy change when.,
1) 1 mol of water is vaporised at 1 bar pressure and 100degree Celsius.
2)1 mol of water is converted into ice.

Answer 1

Assuming that water vapor is an ideal gas, the internal energy change (ΔUΔU) when 1 mole of water is vaporized at 1 bar pressure and 100∘C100∘C (molar enthalpy of vaporization of water at 1 bar and 373 K = 41 kJ/mol and R = 8.314 J/Kmol) will be

(A)4.100kJ/mol(C)37.904kJ/mol(B)3.7904kJ/mol(D)41.00kJ/mol

Answer Is D