A solution of a non-volatile solute in water freezes at `-0.30^(@)C`. The vapour pressure of pure water at `298 K` is `23.51 mm Hg` and `K_(f)` for water is `1.86 degree//molal`. Calculate the vapour pressure of this solution at `298 K`.

Explanation

`DeltaT=K_(f)xx` Molality
`0.3=1.86xx` Molality
Molality = 0.161
Molality `= (x_(B)xx1000)/((1-x_(B))xxm_(A))`
`0.161=(x_(B)xx1000)/((1-x_(B))18)`
`X_(A)=0.00289`
`(Deltap)/(p_(0))=x_(B)`
`(23.51-p_(s))/(23.51)=0.00289`
`p_(s)=23.442` mm.