When one mol of an allotropic form of a compound A ( density 2.45gcm−3 changes to its another form B (density 2.31gcm−3J internal energy change was found to lie 190 J. Calculate the enthalpy change when the pressure is 1.1bar and mol. wt. of compound is 84.

P=1.1bar=1.1×105Pa; VB= mass  density =842.81;VASo,                 ΔV=VB−VA                           =842.81−842.45=84×2.45−84×2.812.81×2.45                         =205.8−236.042.81×2.45=−30.24cm3mol−=−30.24×10−6m3mol−Δll=190Jmol−∴ ΔH=ΔU+PΔV;ΔH=190Jnol−+1.1×105PaorNm−2×−30.24×10−6m3mol−=190Jmol−−3.33Nmmol−=190Jmol−−3.33Jmol−[1⋅1Nm=1J]=186.67Jmol−