1.

A solution of sucrose (molar mass =324 g/mol) is prepared by dissolving 68.4 g in 1000 g of water. What is the freezing point and boiling point of the solution ? K_(f)= water is 1.86 K/mand K_(b) =0.52 K/m.

Answer»


SOLUTION :`M_(B)=342" g mol"^(-1), W_(B)=68.4 g, W_(A)=1 KG,`
`K_(f)=1.86Km^(-1), K_(b)=0.52Km^(-1),T_(f)=?, T_(b)=?`
`DeltaT_(f)=(K_(f)xxW_(B))/(M_(B)xxW_(A))""DeltaT_(f)=(K_(b)xxW_(B))/(M_(B)xxW_(A))`
`=((186" K kg mol"^(-1))xx(68.4 g))/((342" g mol"^(-1))xx(1kg)),""DeltaT_(b)=((0.52" K kg mol"^(-1))xx(68.4g))/((342g)xx(1 kg))`
`=0.372 K,"" =0.104 K`
`T_(f)=T_(f)^(@)-DeltaT_(f)=273-0.372,""T_(b)=T_(b)^(@)+DeltaT_(b)=373+0.104`
`=272.628 K""=373.104 K`


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