An aqueus ideal solution of liquid 'x' (molecular mass 56) 28% by weight has vapour pressure os 150 mm. Find the vapour pressure of 'X' if vapour pressure of water is 155 mm Hg.

Explanation

`"No. of. Of moles of "X (n_(B))= ("Mass of X")/("Molar mass of X")=(28g)/(56g mol^(-1))=0.5 mol`
`" No. of moles of water" (n_(B))=("Mass of water")/("Molar mass of water")=((72g))/(((0.5+4.0))mol)=1/9`
` "Mole fraction of water "(x_(A))=1-1x_(B)=1-1/9=8/9`
` "Partial vapouir pessure of "X(P_(B))= P_(B)^(@)x_(B)=P_(B)^(@)xx1//9`
` (p^(@)"b is the vpur pressure of X")`
Partialpressure of aqueus solution (p)=150mm(given)
For an ideal solution, `p=pA+pB`
`(150 m)=(155 mm)xx8/0+p_(B)^(@)xx1//9`
`P_(B)^(@)=(150-137.8)9=12.2xx9=109.8=110 mm`