The molar heats of fusion and vapourisation of benzene are 10.9 and 31.0 ~kJ ~mol ⁻¹ respectively. The changes in entropy for the solid liquid and liquid vapour transitions for benzene are x and y . JK ⁻¹ ~mol ⁻¹ , respectively. The value of (y-x) ( . in . JK ⁻¹ ~mol ⁻¹ ) is (At 1 atm, benzene melts at 5.5^ C and boils at 80^ C )

Step-by-step solution

aligned & H _ fus ( C ₆ H ₆ )=10.9 ~kJ ~mol ⁻¹ & H _ vap ( C ₆ H ₆ )=31.0 ~kJ ~mol ⁻¹ & Melting point of benzene =5.5^ C & =(5.5+273.15) K & =278.65 ~K & Boiling point of benzene =80^ C & =(80+273.15) K & =353.15 ~K & y - x = H _ vap T _ b.p - H _ fus T _ m . p aligned aligned & = 31 1000 353.15 - 10.9 1000 278.65 & =48.66 JK ⁻¹ ~mol ⁻¹ aligned