Question

Question #d9acc

Answer 1

Given

`V->"Volume of the gaseous solute"=4L`

`P->"Pressure of the gaseous solute"=748mm=748/760atm`

`T->"Pressure of the gaseous solute"=27^@C=300K`

`n->"Number of moles of the gaseous solute"=?`

`R->"Universal gas constant"=0.082LatmK^-1mol^-1`

By equation of state for ideal gas

`PV=nRT`

`=>n=(PV)/(RT)=(748/760xx4)/(0.082xx300)=0.16mol`

Mass of solvent (benzene)`=58g=0.058kg`

Molality of the solution

`="moles of solute"/"mass of solvent in kg"`

`=0.16/0.058=2.76m`

The depression of freezing point

`DeltaT_f="molality"xxK_f`

`=2.76xx5.12=14.13^@`