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The boiling point ofbenzene rises from 80.1^(@)C to 13.76g of biphenyl (C_(6)H_(5)-C_(6)H_(5)) is dissolved into 100 g of benzene. Calculate latent heat of vaporisation of benzene. |
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Answer» Solution :Calculation of molal ELEVATION constant `(K_(B))` for benzene `DeltaT_(b)=(1000k_(b)w_(2))/(w_(1)M_(2))or K_(b)=(DeltaT_(b)xxw_(1)xxM_(2))/(1000xxw_(2))=((82.4-80.1)Kxx100gxx"154 g mol"^(-1))/("1000 g kg"^(-1)xx13.76g)="2.574 K kg mol"^(-1)` Calculation of `Delta_("vap")H` `K_(b)=(M_(1)RT_(0)^(2))/(1000Delta_("vap")H)or Delta_("vap")H=(M_(1)RT_(0)^(2))/(1000K_(b))=("78 g mol"^(-1)xx8.314" jK"^(-1)"mol"^(-1)xx(8.01+273)^(2)K^(2))/("1000 g kg"^(-1)xx2.574"K kg mol"^(-1))` `="31411 J mol"^(-1)=31.411" kJ mol"^(-1)` |
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